external/libgpg-error: -Werror,-Wundef (clang-cl)

Change-Id: I7e71411901cc2c09b5d13a5ca451f1981e8a9e44
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/100090
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/libgpg-error/UnpackedTarball_libgpg-error.mk

@@ -21,6 +21,7 @@ $(eval $(call gb_UnpackedTarball_add_patches,libgpg-error, \
 	external/libgpg-error/w32-build-fixes-4.patch \
 	$(if $(filter MSC,$(COM)),external/libgpg-error/w32-build-fixes-5.patch) \
 	$(if $(filter LINUX,$(OS)),external/libgpg-error/libgpgerror-bundled-soname.patch.1) \
+	external/libgpg-error/clang-cl.patch \
 ))
 
 # vim: set noet sw=4 ts=4:

external/libgpg-error/clang-cl.patch

@@ -0,0 +1,11 @@
+--- src/gpg-error.h.in
++++ src/gpg-error.h.in
+@@ -152,7 +152,7 @@
+ /*
+  * GCC feature test.
+  */
+-#if __GNUC__
++#ifdef __GNUC__
+ # define _GPG_ERR_GCC_VERSION (__GNUC__ * 10000 \
+                                + __GNUC_MINOR__ * 100 \
+                                + __GNUC_PATCHLEVEL__)