Fix buffer underrun in configuration test harness.

If the total bytes read from the expect log file was 0 then the last byte of whatever was in memory before harnessLogBuffer would be set to 0.

On 32-bit systems this expressed as the high order byte of a pointer being cleared and wackiness (in the form of segfaults) ensued.

doc/xml/release.xml

@@ -105,6 +105,10 @@
 
             <release-test-list>
                 <release-development-list>
+                    <release-item>
+                        <p>Fix buffer underrun in configuration test harness.</p>
+                    </release-item>
+
                     <release-item>
                         <p>Make Valgrind return an error even when a non-fatal issue is detected.  Update some minor issues discovered in the tests as a result.</p>
                     </release-item>

test/src/common/harnessLog.c

@@ -142,6 +142,7 @@ harnessLogLoad(const char *logFile)
         THROW_SYS_ERROR_FMT(FileOpenError, "unable to close log file '%s'", logFile);
 
     // Remove final linefeed
+    if (totalBytes > 0)
         harnessLogBuffer[totalBytes - 1] = 0;
 
     FUNCTION_HARNESS_RESULT_VOID();