merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/contrib/svn-fe/svn-fe.c

@@ -0,0 +1,18 @@
+/*
+ * This file is in the public domain.
+ * You may freely use, modify, distribute, and relicense it.
+ */
+
+#include <stdlib.h>
+#include "svndump.h"
+
+int main(int argc, char **argv)
+{
+	if (svndump_init(NULL))
+		return 1;
+	svndump_read((argc > 1) ? argv[1] : NULL, "refs/heads/master",
+			"refs/notes/svn/revs");
+	svndump_deinit();
+	svndump_reset();
+	return 0;
+}