fstools: add missing #define _GNU_SOURCE

asprintf requires _GNU_SOURCE to be defined. Set it.

Signed-off-by: Daniel Golle <[email protected]>

package/system/fstools/Makefile

@@ -12,9 +12,9 @@ PKG_RELEASE:=$(AUTORELEASE)
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(PROJECT_GIT)/project/fstools.git
-PKG_MIRROR_HASH:=98a82c9387f248f57f30c88e6b8cc3cae1d6a83bf39d1ef92ca853c638082b9d
+PKG_MIRROR_HASH:=41c9c51d193f5150db67fcd898b6ea904b88476c94cdfd021d81e2711441b430
 PKG_SOURCE_DATE:=2021-05-16
-PKG_SOURCE_VERSION:=2aeba8876ae75f4492093bd06b3a7c2b65805541
+PKG_SOURCE_VERSION:=3d40a1b591cd569f95891116cd033b496de0f92b
 CMAKE_INSTALL:=1
 
 PKG_LICENSE:=GPL-2.0