[Mips] For MIPS '-fPIC -static' means to compile as -fPIC but link with
-static. So do not turn off the PIC flag if -static passed to the
driver in case of MIPS target.

http://llvm.org/bugs/show_bug.cgi?id=14693

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191947 91177308-0d34-0410-b5e6-96231b3b80d8