Merge branch 'fc/fast-export-persistent-marks'

Optimization for fast-export by avoiding unnecessarily resolving
arbitrary object name and parsing object when only presence and
type information is necessary, etc.

* fc/fast-export-persistent-marks:
  fast-{import,export}: use get_sha1_hex() to read from marks file
  fast-export: don't parse commits while reading marks file
  fast-export: do not parse non-commit objects while reading marks file

fast-import.c

@@ -1822,7 +1822,7 @@ static void read_marks(void)
 		*end = 0;
 		mark = strtoumax(line + 1, &end, 10);
 		if (!mark || end == line + 1
-			|| *end != ' ' || get_sha1(end + 1, sha1))
+			|| *end != ' ' || get_sha1_hex(end + 1, sha1))
 			die("corrupt mark line: %s", line);
 		e = find_object(sha1);
 		if (!e) {