v8: cherry-pick uclibc build patch from upstream
Original commit log follows:
Restore V8_LIBC_UCLIBC as a libc option.
As uClibc defines __GLIBC__ in an attempt to look like glibc,
V8_LIBC_GLIBC was true for uClibc as well. Checking for uClibc
before glibc fixes this and restores the correct behavior.
Review URL: https://codereview.chromium.org/
1066573005
Fixes: https://github.com/nodejs/io.js/issues/1432
PR-URL: https://github.com/nodejs/io.js/pull/1974
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Rod Vagg <rod@vagg.org>