*: merge some common strings

text   data    bss    dec    hexfilename
 838650   8009      0 846659  ceb43busybox_old
 838519   8009      0 846528  ceac0busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

libbb/run_shell.c

@@ -86,5 +86,5 @@ void FAST_FUNC run_shell(const char *shell, int loginshell, const char *command,
 		freecon(current_sid);
 #endif
 	execv(shell, (char **) args);
-	bb_perror_msg_and_die("can't run %s", shell);
+	bb_perror_msg_and_die("can't run '%s'", shell);
 }