Dropped the parentheses for #pragma message and its kin in the -E output generator.

This was a suggestion by Jordan Rose since the documented format for these pragmas is without the parentheses.  At the same time, I've increased test coverage too for the preprocessed output.

llvm-svn: 179771
diff --git a/clang/test/Lexer/pragma-operators.cpp b/clang/test/Lexer/pragma-operators.cpp
index 6a5a498..7402f9f 100644
--- a/clang/test/Lexer/pragma-operators.cpp
+++ b/clang/test/Lexer/pragma-operators.cpp
@@ -32,6 +32,6 @@
 // CHECK: #pragma comment(lib, "libfoo")
 // CHECK: #pragma clang diagnostic ignored "-Wunused"
 // CHECK: #pragma clang diagnostic error "-Wunused"
-// CHECK: #pragma message("\042Hello\042, world!")
+// CHECK: #pragma message "\042Hello\042, world!"
 // CHECK: 0;
 int n = pragma_L pragma_u8 pragma_u pragma_U pragma_R pragma_UR pragma_hello 0;