kselftest/arm64: Include <asm/ptrace.h> for user_gcs definition

kselftest includes kernel uAPI headers with option:

  -isystem $(top_srcdir)/usr/include

Include <asm/ptrace.h> in libc-gcs.c for the definition of struct
user_gcs from the uAPI headers, and remove the redundant definition in
gcs-util.h. This fixes a compilation error on systems where the
toolchain defines NT_ARM_GCS.

Fixes: a505a52 ("kselftest/arm64: Add a GCS test program built with the system libc")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: Leo-Yan

tools/testing/selftests/arm64/gcs/gcs-util.h

@@ -18,12 +18,6 @@
 
 #ifndef NT_ARM_GCS
 #define NT_ARM_GCS 0x410
-
-struct user_gcs {
-	__u64 features_enabled;
-	__u64 features_locked;
-	__u64 gcspr_el0;
-};
 #endif
 
 /* Shadow Stack/Guarded Control Stack interface */

tools/testing/selftests/arm64/gcs/libc-gcs.c

@@ -16,6 +16,7 @@
 
 #include <asm/hwcap.h>
 #include <asm/mman.h>
+#include <asm/ptrace.h>
 
 #include <linux/compiler.h>