Make host ARM CPU feature detection independent of the vendor

For ARM on linux we use /proc/cpuinfo to detect the host CPU's features.
Linux derives these values without ever looking at the vendor of the
specific CPU implementation. Hence, it adds little value, if we parse
the output of /proc/cpuinfo only for certain vendors.

This patch enables us to derive the correct feature flags e.g. for Qualcomm
CPUs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183790 91177308-0d34-0410-b5e6-96231b3b80d8