OPENSSL_COMPILE_ASSERT implements a static assertion, but the error
message is a little weird because it's a hack around the fact that C,
traditionally, doesn't have static assertions.
C11 now does have _Static_assert (a.k.a. static_assert when one includes
assert.h) so we can use that when provided to get cleaner error
messages.
Change-Id: Ia3625dfb2988de11fd95ddba957f118c0d3183ff
Reviewed-on: https://boringssl-review.googlesource.com/4770
Reviewed-by: Adam Langley <agl@google.com>
daaff93464