Bump the -Wshadow cutoff to 4.8 rather than 4.6.

Per https://gcc.gnu.org/gcc-4.8/changes.html, -Wshadow was made less
trigger-happy starting 4.8.

Change-Id: I023919dea3497e2dd27679a6f0c4a114c0b30337
Reviewed-on: https://boringssl-review.googlesource.com/3730
Reviewed-by: Adam Langley <agl@google.com>
1 file changed