Don't say /proc in macro errors

It's possible that a procfs mounted somewhere other than /proc
is in use.
Signed-off-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/util.h

@@ -137,7 +137,7 @@ extern int do_open_proc(pid_t pid, int flags, const char *fmt, ...);
 		int __fd = do_open_proc(pid, flags,			\
 					fmt, ##__VA_ARGS__);		\
 		if (__fd < 0)						\
-			pr_perror("Can't open /proc/%d/" fmt,	\
+			pr_perror("Can't open %d/" fmt " on procfs",	\
 					pid, ##__VA_ARGS__);		\
 									\
 		__fd;							\
@@ -161,7 +161,7 @@ extern int do_open_proc(pid_t pid, int flags, const char *fmt, ...);
 			__d = fdopendir(__fd);				\
 			if (__d == NULL)				\
 				pr_perror("Can't fdopendir %d "		\
-					"(/proc/%d/" fmt ")",		\
+					"(%d/" fmt " on procfs)",	\
 					__fd, pid, ##__VA_ARGS__);	\
 		}							\
 		__d;							\
@@ -177,7 +177,7 @@ extern int do_open_proc(pid_t pid, int flags, const char *fmt, ...);
 			__f = fdopen(__fd, "r");			\
 			if (__f == NULL)				\
 				pr_perror("Can't fdopen %d "		\
-					"(/proc/%d/" fmt ")",		\
+					"(%d/" fmt " on procfs)",	\
 					__fd, pid, ##__VA_ARGS__);	\
 		}							\
 		__f;							\