filter: return on null filter from open and close

So that we don't have to include the if(filter) open_filter(filter)
block everywhere, we introduce the guard in the function itself. This
should simplify quite a bit of code.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui-commit.c

@@ -107,28 +107,22 @@ void cgit_print_commit(char *hex, const char *prefix)
 	}
 	html("</table>\n");
 	html("<div class='commit-subject'>");
-	if (ctx.repo->commit_filter)
-		cgit_open_filter(ctx.repo->commit_filter);
+	cgit_open_filter(ctx.repo->commit_filter);
 	html_txt(info->subject);
-	if (ctx.repo->commit_filter)
-		cgit_close_filter(ctx.repo->commit_filter);
+	cgit_close_filter(ctx.repo->commit_filter);
 	show_commit_decorations(commit);
 	html("</div>");
 	html("<div class='commit-msg'>");
-	if (ctx.repo->commit_filter)
-		cgit_open_filter(ctx.repo->commit_filter);
+	cgit_open_filter(ctx.repo->commit_filter);
 	html_txt(info->msg);
-	if (ctx.repo->commit_filter)
-		cgit_close_filter(ctx.repo->commit_filter);
+	cgit_close_filter(ctx.repo->commit_filter);
 	html("</div>");
 	if (notes.len != 0) {
 		html("<div class='notes-header'>Notes</div>");
 		html("<div class='notes'>");
-		if (ctx.repo->commit_filter)
-			cgit_open_filter(ctx.repo->commit_filter);
+		cgit_open_filter(ctx.repo->commit_filter);
 		html_txt(notes.buf);
-		if (ctx.repo->commit_filter)
-			cgit_close_filter(ctx.repo->commit_filter);
+		cgit_close_filter(ctx.repo->commit_filter);
 		html("</div>");
 		html("<div class='notes-footer'></div>");
 	}