Build fc-cache tool with -std=gnu99 instead of -std=c99 to get necessary

function prototypes on gcc-14/glibc build hosts.

Author: jakllsch

external/mit/xorg/tools/fc-cache/Makefile

@@ -1,4 +1,4 @@
-#	$NetBSD: Makefile,v 1.23 2025/07/20 12:32:19 hans Exp $
+#	$NetBSD: Makefile,v 1.24 2025/10/13 14:03:47 jakllsch Exp $
 
 .include <bsd.hostinit.mk>
 
@@ -89,7 +89,7 @@ SRCS.expat=	xmlparse.c xmltok.c xmlrole.c
 SRCS=	${SRCS.fc-cache} ${SRCS.fontconfig} ${SRCS.freetype} ${SRCS.expat}
 
 # XXX FONTCONFIG_PATH was arbitrarily chosen
-HOST_CFLAGS=	-std=c99
+HOST_CFLAGS=	-std=gnu99
 HOST_CPPFLAGS=	-DFONTCONFIG_PATH='"${DESTDIR}/etc/X11/fonts"' \
 		-DFC_DEFAULT_FONTS='"${X11FONTDIR}/Type1"' \
 		-DFC_TEMPLATEDIR='"${DESTDIR}${X11FONTDIR}"' \