Fix ECPG compiler warning.

Commit 9b4d52f2095be96ca238ce41f6963ec56376491f failed to notice
that pg_regress_ecpg needed updating.

This patch was independently submitted by both David Rowley
and Andres Freund.

src/interfaces/ecpg/test/pg_regress_ecpg.c

@@ -159,7 +159,7 @@ ecpg_start_test(const char *testname,
 }
 
 static void
-ecpg_init(void)
+ecpg_init(int argc, char *argv[])
 {
 	/* nothing to do here at the moment */
 }