worktree: force convert to int64 to support 32bit os. Fix src-d#1202

Signed-off-by: Antoine GIRARD <[email protected]>

Author: sapk

worktree_linux.go

@@ -12,7 +12,7 @@ import (
 func init() {
 	fillSystemInfo = func(e *index.Entry, sys interface{}) {
 		if os, ok := sys.(*syscall.Stat_t); ok {
-			e.CreatedAt = time.Unix(os.Ctim.Sec, os.Ctim.Nsec)
+			e.CreatedAt = time.Unix(int64(os.Ctim.Sec), int64(os.Ctim.Nsec))
 			e.Dev = uint32(os.Dev)
 			e.Inode = uint32(os.Ino)
 			e.GID = os.Gid