clang defines __arm which is interpreted as non-posix by make build
system but thats not correct when using clang so patch addresses that
(From OE-Core rev: e225278a8a894389add56d14908398c14512f6c9)
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>