[mips] Add test case to check ABI flag emissions in case of inline assembler

Follow up to r247546. The test case reproduces the problem fixed by this commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@247548 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/mips-inline-asm-abi.c

@@ -0,0 +1,12 @@
+// REQUIRES: mips-registered-target
+// RUN: %clang_cc1 -triple mips-linux-gnu -emit-obj -o - %s | \
+// RUN:   llvm-readobj -h - | FileCheck %s
+
+// CHECK: EF_MIPS_ABI_O32
+
+__asm__(
+"bar:\n"
+"  nop\n"
+);
+
+void foo() {}