diff: add interhunk context config option

The --inter-hunk-context= option was added in commit 6d0e674a5754
("diff: add option to show context between close hunks"). This patch
allows configuring a default for this option.

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.c b/diff.c
index e2eb6d6..f08cd8e 100644
--- a/diff.c
+++ b/diff.c
@@ -32,6 +32,7 @@ static int diff_rename_limit_default = 400;
 static int diff_suppress_blank_empty;
 static int diff_use_color_default = -1;
 static int diff_context_default = 3;
+static int diff_interhunk_context_default;
 static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
 static const char *diff_order_file_cfg;
@@ -239,6 +240,12 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 			return -1;
 		return 0;
 	}
+	if (!strcmp(var, "diff.interhunkcontext")) {
+		diff_interhunk_context_default = git_config_int(var, value);
+		if (diff_interhunk_context_default < 0)
+			return -1;
+		return 0;
+	}
 	if (!strcmp(var, "diff.renames")) {
 		diff_detect_rename_default = git_config_rename(var, value);
 		return 0;
@@ -3362,6 +3369,7 @@ void diff_setup(struct diff_options *options)
 	options->rename_limit = -1;
 	options->dirstat_permille = diff_dirstat_permille_default;
 	options->context = diff_context_default;
+	options->interhunkcontext = diff_interhunk_context_default;
 	options->ws_error_highlight = ws_error_highlight_default;
 	DIFF_OPT_SET(options, RENAME_EMPTY);