git-format-patch: add --no-binary to omit binary changes in the patch.

Add a new option --no-binary to git-format-patch so that no binary
changes are included in the generated patches, only notices that those
files changed.  This generate patches that cannot be applied, but still
is useful for generating mails for code review purposes.

See also: commit e47f306d4b, where --binary
option was turned on by default.

Signed-off-by: Caio Marcelo de Oliveira Filho <cmarcelo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-format-patch.txt

@@ -156,6 +156,12 @@ want a filename like `0001-description-of-my-change.patch`, and
 the first letter does not have to be a dot.  Leaving it empty would
 not add any suffix.
 
+--no-binary::
+	Don't output contents of changes in binary files, just take note
+	that they differ.  Note that this disable the patch to be properly
+	applied.  By default the contents of changes in those files are
+	encoded in the patch.
+
 CONFIGURATION
 -------------
 You can specify extra mail header lines to be added to each message

builtin-log.c

@@ -757,6 +757,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	int thread = 0;
 	int cover_letter = 0;
 	int boundary_count = 0;
+	int no_binary_diff = 0;
 	struct commit *origin = NULL, *head = NULL;
 	const char *in_reply_to = NULL;
 	struct patch_ids ids;
@@ -862,6 +863,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			fmt_patch_suffix = argv[i] + 9;
 		else if (!strcmp(argv[i], "--cover-letter"))
 			cover_letter = 1;
+		else if (!strcmp(argv[i], "--no-binary"))
+			no_binary_diff = 1;
 		else
 			argv[j++] = argv[i];
 	}
@@ -914,7 +917,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (!rev.diffopt.output_format)
 		rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_SUMMARY | DIFF_FORMAT_PATCH;
 
-	if (!DIFF_OPT_TST(&rev.diffopt, TEXT))
+	if (!DIFF_OPT_TST(&rev.diffopt, TEXT) && !no_binary_diff)
 		DIFF_OPT_SET(&rev.diffopt, BINARY);
 
 	if (!output_directory && !use_stdout)