libcom: detect uclibc support for backtrace()

modules/libcom/src/osi/os/posix/osdExecinfoBackTrace.cpp

@@ -7,12 +7,30 @@
  * Author: Till Straumann <strauman@slac.stanford.edu>, 2011, 2014
  */ 
 
+// pull in libc feature test macros
+#include <stdlib.h>
+
+// execinfo.h may not be present if uclibc is configured to omit backtrace()
+#if !defined(__UCLIBC_MAJOR__) || defined(__UCLIBC_HAS_EXECINFO__)
+#  define HAS_EXECINFO 1
+#else
+#  define HAS_EXECINFO 0
+#endif
+
+#if HAS_EXECINFO
+
 #include <execinfo.h>
 
+#endif
+
 #define epicsExportSharedSymbols
 #include "epicsStackTracePvt.h"
 
 int epicsBackTrace(void **buf, int buf_sz)
 {
+#if HAS_EXECINFO
 	return backtrace(buf, buf_sz);
+#else
+	return -1;
+#endif
 }