More porting to GCC 8 of --enable-gcc-warnings

Backport from master.
I ran into this when building Emacs 26 with GCC 8 on Fedora 29 x86.
* lwlib/lwlib-Xaw.h (xaw_update_one_value, xaw_popup_menu):
* lwlib/lwlib-Xlw.h (xlw_update_one_value, xlw_pop_instance):
* lwlib/lwlib.h (lw_allow_resizing, lw_set_main_areas) [!USE_MOTIF]:
No longer const.
* src/emacs-module.c: Ignore -Wcast-function-type.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/emacs-module.c b/src/emacs-module.c
index c20902d0729..88049d29cf0 100644
--- a/src/emacs-module.c
+++ b/src/emacs-module.c
@@ -36,6 +36,11 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <intprops.h>
 #include <verify.h>
 
+/* This module is lackadaisical about function casts.  */
+#if GNUC_PREREQ (8, 0, 0)
+# pragma GCC diagnostic ignored "-Wcast-function-type"
+#endif
+
 /* We use different strategies for allocating the user-visible objects
    (struct emacs_runtime, emacs_env, emacs_value), depending on
    whether the user supplied the -module-assertions flag.  If