prune: allow --dry-run for -n and --verbose for -v

For consistency with other git commands, let git prune accept the long
options --dry-run and --verbose for the respective short ones -n and -v.
Signed-off-by: NRene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-prune.txt

@@ -31,10 +31,12 @@ OPTIONS
 -------
 
 -n::
+--dry-run::
 	Do not remove anything; just report what it would
 	remove.
 
 -v::
+--verbose::
 	Report all removed objects.
 
 \--::

builtin/prune.c

@@ -125,10 +125,9 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info revs;
 	const struct option options[] = {
-		OPT_BOOLEAN('n', NULL, &show_only,
+		OPT_BOOLEAN('n', "dry-run", &show_only,
 			    "do not remove, show only"),
-		OPT_BOOLEAN('v', NULL, &verbose,
-			"report pruned objects"),
+		OPT_BOOLEAN('v', "verbose", &verbose, "report pruned objects"),
 		OPT_DATE(0, "expire", &expire,
 			 "expire objects older than <time>"),
 		OPT_END()