tools/proftool: fix use-after-free

The read_trace_config() can dereference the line pointer after freeing
it on its error path. Avoid that.

This was found by Coverity Scan.

Signed-off-by: Vincent Stehlé <vincent.stehle@freescale.com>
Cc: Simon Glass <sjg@chromium.org>

tools/proftool.c

@@ -432,9 +432,10 @@ static int read_trace_config(FILE *fin)
 
 		err = regcomp(&line->regex, tok, REG_NOSUB);
 		if (err) {
+			int r = regex_report_error(&line->regex, err,
+						   "compile", tok);
 			free(line);
-			return regex_report_error(&line->regex, err, "compile",
-						  tok);
+			return r;
 		}
 
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