Add configure script for improved multi-platform support.

Use autoconf to provide a basic configure script. WITH_BACKTRACE is yet to be migrated to configure and the unit tests still use a custom Makefile.

Each C file must include "build.auto.conf" before all other includes and defines.  This is enforced by test.pl for includes, but it won't detect incorrect define ordering.

Update packages to call configure and use standard flags to pass options.

src/postgres/interface.c

@@ -1,6 +1,8 @@
 /***********************************************************************************************************************************
 PostgreSQL Interface
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #include <string.h>
 
 #include "common/debug.h"

src/postgres/interface/v083.c

@@ -3,6 +3,8 @@ PostgreSQL 8.3 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_83
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v084.c

@@ -3,6 +3,8 @@ PostgreSQL 8.4 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_84
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v090.c

@@ -3,6 +3,8 @@ PostgreSQL 9.0 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_90
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v091.c

@@ -3,6 +3,8 @@ PostgreSQL 9.1 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_91
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v092.c

@@ -3,6 +3,8 @@ PostgreSQL 9.2 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_92
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v093.c

@@ -3,6 +3,8 @@ PostgreSQL 9.3 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_93
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v094.c

@@ -3,6 +3,8 @@ PostgreSQL 9.4 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_94
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v095.c

@@ -3,6 +3,8 @@ PostgreSQL 9.5 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_95
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v096.c

@@ -3,6 +3,8 @@ PostgreSQL 9.6 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_96
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v100.c

@@ -3,6 +3,8 @@ PostgreSQL 10 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_10
 
 #include "postgres/interface/version.intern.h"

src/postgres/interface/v110.c

@@ -3,6 +3,8 @@ PostgreSQL 11 Interface
 
 See postgres/interface/version.intern.h for documentation.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #define PG_VERSION                                                  PG_VERSION_11
 
 #include "postgres/interface/version.intern.h"

src/postgres/pageChecksum.c

@@ -62,6 +62,8 @@ calculate a subset of the columns at a time and perform multiple passes to avoid
 is not used. Current coding also assumes that the compiler has the ability to unroll the inner loop to avoid loop overhead and
 minimize register spilling. For less sophisticated compilers it might be beneficial to manually unroll the inner loop.
 ***********************************************************************************************************************************/
+#include "build.auto.h"
+
 #include <string.h>
 
 #include "common/debug.h"