Add Clang Asflags for mips

Like make, it needs -fPIC to be added to compile successfully.

Change-Id: I1d6f1388c42a84f331bbce1ecd669669441d986e

cc/cc.go

@@ -566,6 +566,7 @@ func (c *CCBase) collectFlags(ctx common.AndroidModuleContext, toolchain Toolcha
 		flags.GlobalFlags = append(flags.GlobalFlags, instructionSetFlags)
 
 		if flags.Clang {
+			flags.AsFlags = append(flags.AsFlags, toolchain.ClangAsflags())
 			flags.CppFlags = append(flags.CppFlags, "${commonClangGlobalCppflags}")
 			flags.GlobalFlags = append(flags.GlobalFlags,
 				toolchain.ClangCflags(),