memory: avoid leaking the speller or linter command string, when invoked

This fixes https://savannah.gnu.org/bugs/?59854.
Reported-by: Mike Frysinger <vapier@gentoo.org>

Bug existed probably since version 2.9.6, commit 94347f08.

src/text.c

@@ -2142,13 +2142,17 @@ void treat(char *tempfile_name, char *theprogram, bool spelling)
 
 	if (thepid < 0) {
 		statusline(ALERT, _("Could not fork: %s"), strerror(errornumber));
+		free(arguments[0]);
 		return;
 	} else if (!WIFEXITED(program_status) || WEXITSTATUS(program_status) > 2) {
 		statusline(ALERT, _("Error invoking '%s'"), arguments[0]);
+		free(arguments[0]);
 		return;
 	} else if (WEXITSTATUS(program_status) != 0)
 		statusline(ALERT, _("Program '%s' complained"), arguments[0]);
 
+	free(arguments[0]);
+
 	/* When the temporary file wasn't touched, say so and leave. */
 	if (timestamp_sec > 0 && stat(tempfile_name, &fileinfo) == 0 &&
 					(long)fileinfo.st_mtim.tv_sec == timestamp_sec &&
@@ -2561,7 +2565,6 @@ void do_linter(void)
 	int lint_status, lint_fd[2];
 	pid_t pid_lint;
 	bool helpless = ISSET(NO_HELP);
-	static char **lintargs = NULL;
 	lintstruct *lints = NULL, *tmplint = NULL, *curlint = NULL;
 	time_t last_wait = 0;
 
@@ -2600,10 +2603,10 @@ void do_linter(void)
 	currmenu = MLINTER;
 	statusbar(_("Invoking linter..."));
 
-	construct_argument_list(&lintargs, openfile->syntax->linter, openfile->filename);
-
 	/* Fork a process to run the linter in. */
 	if ((pid_lint = fork()) == 0) {
+		char **lintargs = NULL;
+
 		/* Redirect standard output and standard error into the pipe. */
 		if (dup2(lint_fd[1], STDOUT_FILENO) < 0)
 			exit(7);
@@ -2613,6 +2616,8 @@ void do_linter(void)
 		close(lint_fd[0]);
 		close(lint_fd[1]);
 
+		construct_argument_list(&lintargs, openfile->syntax->linter, openfile->filename);
+
 		/* Start the linter program; we are using $PATH. */
 		execvp(lintargs[0], lintargs);