diff --git a/configure b/configure
index c74e40fc3b..0c16c67215 100755
--- a/configure
+++ b/configure
@@ -3022,11 +3022,9 @@ case $target_os in
         SLIB_INSTALL_EXTRA_LIB='lib$(SLIBNAME:$(SLIBSUF)=.dll.a) $(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
         SHFLAGS='-shared -Wl,--output-def,$$(@:$(SLIBSUF)=.def) -Wl,--out-implib,$(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a) -Wl,--enable-runtime-pseudo-reloc -Wl,--enable-auto-image-base'
         objformat="win32"
+        ranlib=:
         enable dos_paths
         check_cflags -fno-common
-        check_cpp_condition _mingw.h "defined (__MINGW64_VERSION_MAJOR) || (__MINGW32_MAJOR_VERSION > 3) \
-                                      || (__MINGW32_MAJOR_VERSION == 3 && __MINGW32_MINOR_VERSION >= 15)" ||
-                die "ERROR: MinGW runtime version must be >= 3.15."
         add_cppflags -U__STRICT_ANSI__
         ;;
     cygwin*)
@@ -3113,6 +3111,26 @@ case $target_os in
         ;;
 esac
 
+# determine libc flavour
+
+if check_cpp_condition features.h "defined __UCLIBC__"; then
+    libc_type=uclibc
+elif check_cpp_condition features.h "defined __GLIBC__"; then
+    libc_type=glibc
+elif check_header _mingw.h; then
+    libc_type=mingw
+    check_cpp_condition _mingw.h \
+        "defined (__MINGW64_VERSION_MAJOR) || (__MINGW32_MAJOR_VERSION > 3) || \
+            (__MINGW32_MAJOR_VERSION == 3 && __MINGW32_MINOR_VERSION >= 15)" ||
+        die "ERROR: MinGW runtime version must be >= 3.15."
+elif check_cpp_condition newlib.h "defined _NEWLIB_VERSION"; then
+    libc_type=newlib
+elif check_cpp_condition stddef.h "defined __KLIBC__"; then
+    libc_type=klibc
+fi
+
+test -n "$libc_type" && enable $libc_type
+
 esc(){
     echo "$*" | sed 's/%/%25/g;s/:/%3a/g'
 }
diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h
index 85ac20a6ff..640ca769bc 100644
--- a/libavcodec/dsputil.h
+++ b/libavcodec/dsputil.h
@@ -634,22 +634,26 @@ void ff_mlp_init_x86(DSPContext* c, AVCodecContext *avctx);
 #   define STRIDE_ALIGN 8
 #endif
 
+// Some broken preprocessors need a second expansion
+// to be forced to tokenize __VA_ARGS__
+#define E(x) x
+
 #define LOCAL_ALIGNED_A(a, t, v, s, o, ...)             \
     uint8_t la_##v[sizeof(t s o) + (a)];                \
     t (*v) o = (void *)FFALIGN((uintptr_t)la_##v, a)
 
 #define LOCAL_ALIGNED_D(a, t, v, s, o, ...) DECLARE_ALIGNED(a, t, v) s o
 
-#define LOCAL_ALIGNED(a, t, v, ...) LOCAL_ALIGNED_A(a, t, v, __VA_ARGS__,,)
+#define LOCAL_ALIGNED(a, t, v, ...) E(LOCAL_ALIGNED_A(a, t, v, __VA_ARGS__,,))
 
 #if HAVE_LOCAL_ALIGNED_8
-#   define LOCAL_ALIGNED_8(t, v, ...) LOCAL_ALIGNED_D(8, t, v, __VA_ARGS__,,)
+#   define LOCAL_ALIGNED_8(t, v, ...) E(LOCAL_ALIGNED_D(8, t, v, __VA_ARGS__,,))
 #else
 #   define LOCAL_ALIGNED_8(t, v, ...) LOCAL_ALIGNED(8, t, v, __VA_ARGS__)
 #endif
 
 #if HAVE_LOCAL_ALIGNED_16
-#   define LOCAL_ALIGNED_16(t, v, ...) LOCAL_ALIGNED_D(16, t, v, __VA_ARGS__,,)
+#   define LOCAL_ALIGNED_16(t, v, ...) E(LOCAL_ALIGNED_D(16, t, v, __VA_ARGS__,,))
 #else
 #   define LOCAL_ALIGNED_16(t, v, ...) LOCAL_ALIGNED(16, t, v, __VA_ARGS__)
 #endif
diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index 24bf90a467..713fda7421 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -2845,7 +2845,6 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
             }
         } else {
             /* Frame or first field in a potentially complementary pair */
-//             assert(!s0->current_picture_ptr);
             s0->first_field = FIELD_PICTURE;
         }