Use getauxval() if available.

Use getauxval() if available.

This fixes the problem of not being able to detect ARM features on
ChromeOS because sandbox cannot access /proc/self/auxv and
/proc/cpuinfo there.

Drive-by-cleanup to libc detection in two other places.

R=svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24789

[Benedikt Meurer, 2014-10-22 06:14:28]

bmeurer@chromium.org changed reviewers:
+ svenpanne@chromium.org

[Benedikt Meurer, 2014-10-22 06:14:29]

PTAL

[Benedikt Meurer, 2014-10-22 06:15:07]

https://codereview.chromium.org/672543002/diff/1/include/v8config.h
File include/v8config.h (left):

https://codereview.chromium.org/672543002/diff/1/include/v8config.h#oldcode123
include/v8config.h:123: //  V8_LIBC_UCLIBC  - uClibc
This was unused and crappy, so I removed that on the way.

[Sven Panne, 2014-10-22 06:40:38]

lgtm

[Benedikt Meurer, 2014-10-22 06:42:26]

Committed patchset #1 (id:1) manually as 24789 (presubmit successful).