um: take userland definition of barrier() to user.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/include/shared/process.h

@@ -8,9 +8,6 @@
 
 #include <signal.h>
 
-/* Copied from linux/compiler-gcc.h since we can't include it directly */
-#define barrier() __asm__ __volatile__("": : :"memory")
-
 extern void sig_handler(int sig, struct sigcontext *sc);
 extern void alarm_handler(int sig, struct sigcontext *sc);
 

arch/um/include/shared/user.h

@@ -40,4 +40,7 @@ extern int in_aton(char *str);
 extern size_t strlcpy(char *, const char *, size_t);
 extern size_t strlcat(char *, const char *, size_t);
 
+/* Copied from linux/compiler-gcc.h since we can't include it directly */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
 #endif