Add libexecinfo check for OpenBSD

In order to use backtrace() in error reporting on OpenBSD we need
to link with libexecinfo from ports as backtrace() is a glibc only
addition.

configure

@@ -12294,6 +12294,57 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
+fi
+
+# OpenBSD requires libexecinfo from ports for backtrace() as it's a glibc addition
+if test "$PORTNAME" = "openbsd"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for backtrace in -lexecinfo" >&5
+$as_echo_n "checking for backtrace in -lexecinfo... " >&6; }
+if ${ac_cv_lib_execinfo_backtrace+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lexecinfo  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char backtrace ();
+int
+main ()
+{
+return backtrace ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_execinfo_backtrace=yes
+else
+  ac_cv_lib_execinfo_backtrace=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_execinfo_backtrace" >&5
+$as_echo "$ac_cv_lib_execinfo_backtrace" >&6; }
+if test "x$ac_cv_lib_execinfo_backtrace" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBEXECINFO 1
+_ACEOF
+
+  LIBS="-lexecinfo $LIBS"
+
+else
+  as_fn_error $? "library 'execinfo' is required for backtrace support" "$LINENO" 5
+fi
+
 fi
 
 ##
@@ -13319,6 +13370,24 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+fi
+
+# OpenBSD requires libexecinfo from ports for backtrace() as it's a glibc addition
+if test "$PORTNAME" = "openbsd"; then
+  for ac_header in execinfo.h
+do :
+  ac_fn_c_check_header_mongrel "$LINENO" "execinfo.h" "ac_cv_header_execinfo_h" "$ac_includes_default"
+if test "x$ac_cv_header_execinfo_h" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_EXECINFO_H 1
+_ACEOF
+
+else
+  as_fn_error $? "header file <execinfo.h> is required for backtrace support" "$LINENO" 5
+fi
+
+done
+
 fi
 
 ##

configure.in

@@ -1397,6 +1397,11 @@ if test "$enable_orca" = yes; then
   PGAC_CHECK_ORCA_LIBS
 fi
 
+# OpenBSD requires libexecinfo from ports for backtrace() as it's a glibc addition
+if test "$PORTNAME" = "openbsd"; then
+  AC_CHECK_LIB(execinfo, backtrace, [], [AC_MSG_ERROR([library 'execinfo' is required for backtrace support])])
+fi
+
 ##
 ## Header files
 ##
@@ -1576,6 +1581,11 @@ if test "$enable_orca" = yes; then
   PGAC_CHECK_ORCA_VERSION
 fi
 
+# OpenBSD requires libexecinfo from ports for backtrace() as it's a glibc addition
+if test "$PORTNAME" = "openbsd"; then
+  AC_CHECK_HEADERS([execinfo.h], [], [AC_MSG_ERROR([header file <execinfo.h> is required for backtrace support])])
+fi
+
 ##
 ## Types, structures, compiler characteristics
 ##