package/sbc: fix build with gcc-15.x

Fixes:
https://autobuild.buildroot.net/results/2d1/2d16eb4bb0c7f095d0d52af8553c498f6f9a295c/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/sbc/sbc.mk

@@ -12,6 +12,13 @@ SBC_DEPENDENCIES = host-pkgconf
 SBC_LICENSE := LGPL-2.1+ (library)
 SBC_LICENSE_FILES = COPYING COPYING.LIB
 
+# gcc-15 defaults to -std=gnu23 which introduces build failures.
+# We force "-std=gnu17" for gcc version supporting it. Earlier gcc
+# versions will work, since they are using the older standard.
+ifeq ($(BR2_TOOLCHAIN_GCC_AT_LEAST_8),y)
+SBC_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) -std=gnu17"
+endif
+
 ifeq ($(BR2_PACKAGE_SBC_TOOLS),y)
 SBC_DEPENDENCIES += libsndfile
 SBC_CONF_OPTS += --enable-tools --enable-tester