Allow overriding the location of C/C++ compilers in Android CMake build.

Patch by Greg Fitzgerald.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182831 91177308-0d34-0410-b5e6-96231b3b80d8
Temporary fix to get rid of gcc warning.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182832 91177308-0d34-0410-b5e6-96231b3b80d8