[PATCH, testsuite] Stringify __USER_LABEL_PREFIX__ for pr81923.c

[Iain Sandoe]

Hi,

This test has always failed on Darwin (and presumably the other targets with 
user __USER_LABEL_PREFIX__  != “” ) since it needs to be stringified.

OK for trunk?
affected branches?

thanks
Iain

2018-08-15  Iain Sandoe <i...@sandoe.co.uk>

gcc/testsuite:

        * gcc.dg/asan/pr81923.c: Stringify __USER_LABEL_PREFIX__.

diff --git a/gcc/testsuite/gcc.dg/asan/pr81923.c 
b/gcc/testsuite/gcc.dg/asan/pr81923.c
index f81d512..dd9db72 100644
--- a/gcc/testsuite/gcc.dg/asan/pr81923.c
+++ b/gcc/testsuite/gcc.dg/asan/pr81923.c
@@ -1,7 +1,10 @@
 /* PR sanitizer/81923 */
 /* { dg-do link } */
 
-int foobar __asm (__USER_LABEL_PREFIX__ "barbaz") = 34;
+#define STR1(X) #X
+#define STR2(X) STR1(X)
+
+int foobar __asm (STR2(__USER_LABEL_PREFIX__) "barbaz") = 34;
 
 int
 main ()