[PATCH 2/4] x86, selftests, mpx: fix up weird arrays

[Dave Hansen]

The MPX hardware data structurse are defined in a weird way: they define
their size in bytes and then union that with the type with which we want
to access them.

Yes, this is weird, but it does work.  But, new GCC's complain that we
are accessing the array out of bounds.  Just make it a zero-sized array
so gcc will stop complaining.  There was not really a bug here.

---

 b/tools/testing/selftests/x86/mpx-hw.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN tools/testing/selftests/x86/mpx-hw.h~x86-selftests-mpx-weird-arrays tools/testing/selftests/x86/mpx-hw.h
--- a/tools/testing/selftests/x86/mpx-hw.h~x86-selftests-mpx-weird-arrays	2017-11-10 15:29:24.846207949 -0800
+++ b/tools/testing/selftests/x86/mpx-hw.h	2017-11-10 15:29:24.850207949 -0800
@@ -52,14 +52,14 @@
 struct mpx_bd_entry {
 	union {
 		char x[MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES];
-		void *contents[1];
+		void *contents[0];
 	};
 } __attribute__((packed));
 
 struct mpx_bt_entry {
 	union {
 		char x[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES];
-		unsigned long contents[1];
+		unsigned long contents[0];
 	};
 } __attribute__((packed));
 
_