Turn on mips16 pseudo op when compiling for mips16.
Expand test case for this.

Patch by Reed Kotler.

llvm-svn: 157410
diff --git a/llvm/test/CodeGen/Mips/null.ll b/llvm/test/CodeGen/Mips/null.ll
index a5e2c06..f34f6a4 100644
--- a/llvm/test/CodeGen/Mips/null.ll
+++ b/llvm/test/CodeGen/Mips/null.ll
@@ -5,6 +5,9 @@
 entry:
   ret i32 0
 
+; 16: 	.set	mips16                  # @main
+; 16:	.set	nomicromips
+
 ; 16:	jr	$ra
 
 }