Make .asm a valid extension for assembly files

This is a common extension on Windows, and now clang will assemble them
instead of treating them as linker input which is the default for unknown
file types.

llvm-svn: 192919

clang/lib/Driver/Types.cpp

@@ -139,6 +139,7 @@ types::ID types::lookupTypeForExtension(const char *Ext) {
            .Case("f", TY_PP_Fortran)
            .Case("F", TY_Fortran)
            .Case("s", TY_PP_Asm)
+           .Case("asm", TY_PP_Asm)
            .Case("S", TY_Asm)
            .Case("o", TY_Object)
            .Case("obj", TY_Object)