policycoreutils: newrole: always initialize pw fields

In extract_pw_data(), if "getpwuid(uid)" fails, the function returns an
error value without initializing main's pw.pw_name. This leads main() to
call "free(pw.pw_name)" on an uninitialized value.

Use memset() to initialize structure pw in main().

This issue has been found using clang's static analyzer.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>

policycoreutils/newrole/newrole.c

@@ -1113,6 +1113,7 @@ int main(int argc, char *argv[])
 	 * malicious software), not to authorize the operation (which is covered
 	 * by policy).  Trusted path mechanism would be preferred.
 	 */
+	memset(&pw, 0, sizeof(pw));
 	if (extract_pw_data(&pw))
 		goto err_free;