MIPS: ARM: Log an error if /proc/cpuinfo cannot be opened

Port r14112 (8cc5081c)

Original commit message:
This will make it easier to see if the current CPU feature detection
starts breaking because of process sandboxing.

BUG=

Review URL: https://codereview.chromium.org/13582007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14170 ce2b1a6d-e550-0410-aec6-3dcde31c8c00