Hot-fix ecpg regression test for missing ecpg_config.h inclusion.

I don't think this is really the best long-term answer, and in
particular it doesn't fix the pre-existing hazard in sqltypes.h.
But for the moment let's just try to make the buildfarm green again.

Discussion: https://postgr.es/m/151935568942.1461.14623890240535309745@wrigleys.postgresql.org

src/interfaces/ecpg/test/expected/sql-sqlda.c

@@ -10,6 +10,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include "ecpg_config.h"
 
 
 #line 1 "regression.h"
@@ -19,8 +20,7 @@
 
 
 
-#line 5 "sqlda.pgc"
-
+#line 6 "sqlda.pgc"
 
 
 #line 1 "sqlda.h"

src/interfaces/ecpg/test/sql/sqlda.pgc

@@ -1,9 +1,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include "ecpg_config.h"
 
 exec sql include ../regression;
-
 exec sql include sqlda.h;
 exec sql include pgtypes_numeric.h;