*: make exec failure message more consistent

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

mailutils/mail.c

@@ -67,8 +67,8 @@ void FAST_FUNC launch_helper(const char **argv)
 	if (!G.helper_pid) {
 		// child: try to execute connection helper
 		// NB: SIGCHLD & SIGALRM revert to SIG_DFL on exec
-		BB_EXECVP(*argv, (char **)argv);
-		_exit(127);
+		BB_EXECVP(argv[0], (char **)argv);
+		bb_perror_msg_and_die("can't execute '%s'", argv[0]);
 	}
 
 	// parent

mailutils/mime.c

@@ -288,8 +288,8 @@ static int parse(const char *boundary, char **argv)
 					xsetenv("CHARSET", charset);
 					xsetenv("ENCODING", encoding);
 					xsetenv("FILENAME", filename);
-					BB_EXECVP(*argv, argv);
-					_exit(EXIT_FAILURE);
+					BB_EXECVP(argv[0], argv);
+					bb_perror_msg_and_die("can't execute '%s'", argv[0]);
 				}
 				// parent dumps to fd[1]
 				close(fd[0]);