Warning cleanups for ecpg tests. Avoid doing pointer arithmetic on void *,

remove old-style function declarations, and mark a function "static".
There are some remaining warnings, but this fixes most of them, anyway.

src/interfaces/ecpg/test/num_test.pgc

@@ -3,7 +3,7 @@
 #include <decimal.h>
 
 int
-main()
+main(void)
 {
 	char *text="error\n";
 	numeric *value1, *value2, *res;