mingw: use COPY_ARRAY for copying array

Use the macro COPY_ARRAY to copy array elements.  The result is shorter
and safer, as it infers the element type automatically and does a (very)
basic type compatibility check for its first two arguments.

Coccinelle and contrib/coccinelle/array.cocci did not generate this
conversion due to the offset of 1 at both source and destination and
because the source is a const pointer; the semantic patch cautiously
handles only pure pointers and array references of the same type.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

compat/mingw.c

@@ -1562,7 +1562,7 @@ static int try_shell_exec(const char *cmd, char *const *argv)
 		while (argv[argc]) argc++;
 		ALLOC_ARRAY(argv2, argc + 1);
 		argv2[0] = (char *)cmd;	/* full path to the script file */
-		memcpy(&argv2[1], &argv[1], sizeof(*argv) * argc);
+		COPY_ARRAY(&argv2[1], &argv[1], argc);
 		exec_id = trace2_exec(prog, argv2);
 		pid = mingw_spawnv(prog, argv2, 1);
 		if (pid >= 0) {