ntdll: Use __asm__ keyword instead of asm in signal_sparc.c.

dlls/ntdll/signal_sparc.c

@@ -779,7 +779,7 @@ void signal_init_process(void)
        the process.  wine-devel did not reach a conclusion on whether
        this is correct, because that is what x86 does, or it is harmful 
        because it could obscure problems in user code */
-    asm("ta 6"); /* 6 == ST_FIX_ALIGN defined in sys/trap.h */
+    __asm__("ta 6"); /* 6 == ST_FIX_ALIGN defined in sys/trap.h */
     return;
 
  error: