[PATCH v2] Don't define _FORTIFY_SOURCE on mingw

["Christian Biesinger via gdb-patches" <gdb-patches@sourceware.org>]

Recent mingw versions require -lssp when using _FORTIFY_SOURCE, which
gdb does (in common-defs.h)
https://github.com/msys2/MINGW-packages/issues/5868#issuecomment-544107564

To avoid all the complications with checking for -lssp and making sure it's
linked statically, just don't define it.

gdb/ChangeLog:

2019-12-18  Christian Biesinger  <cbiesinger@google.com>

	* gdbsupport/common-defs.h: Don't define _FORTIFY_SOURCE on mingw.

Change-Id: Ide6870ab57198219a2ef78bc675768a789ca2b1d
---
 gdb/gdbsupport/common-defs.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/gdbsupport/common-defs.h b/gdb/gdbsupport/common-defs.h
index 203bd8972d..53ce3c96ea 100644
--- a/gdb/gdbsupport/common-defs.h
+++ b/gdb/gdbsupport/common-defs.h
@@ -66,9 +66,13 @@
    plus this seems like a reasonable safety measure.  The check for
    optimization is required because _FORTIFY_SOURCE only works when
    optimization is enabled.  If _FORTIFY_SOURCE is already defined,
-   then we don't do anything.  */
+   then we don't do anything.  Also, on mingw, fortify requires
+   linking to -lssp, and to avoid the hassle of checking for
+   that and linking to it statically, we just don't define
+   _FORTIFY_SOURCE there.  */
 
-#if !defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__ > 0
+#if (!defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__ > 0 \
+     && !defined(__MINGW32__))
 #define _FORTIFY_SOURCE 2
 #endif
 
-- 
2.24.1.735.g03f4e72817-goog