Some setups need _GNU_SOURCE to make LLONG_MAX available (thanks, Ozkan!). Fixes Bugzilla #2721.
diff --git a/src/test/SDL_test_fuzzer.c b/src/test/SDL_test_fuzzer.c
index aff4a1c..9fad178 100644
--- a/src/test/SDL_test_fuzzer.c
+++ b/src/test/SDL_test_fuzzer.c
@@ -34,6 +34,7 @@
#define UINT32_MAX ~(Uint32)0
#define UINT64_MAX ~(Uint64)0
#else
+#define _GNU_SOURCE
#include <stdint.h>
#endif
#include <stdio.h>