On Mac for the requested minimal version (10.5) only old stl (from gcc 4.2.1) can be used so unfortunately we can't use numeric_limits<>::lowest() which were added in 874c54e0

BUG=
TEST=cctest/test-assembler-mips64, cctest/test-assembler-mips

Review URL: https://codereview.chromium.org/1175463003

Cr-Commit-Position: refs/heads/master@{#28907}