Fix compilation with GCC 4.8

BUG=v8:2767,v8:2149
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/69413002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17641 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
linux: use CLOCK_{REALTIME,MONOTONIC}_COARSE

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/68203004

Patch from Ben Noordhuis <info@bnoordhuis.nl>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17642 ce2b1a6d-e550-0410-aec6-3dcde31c8c00