[vim] Use async version of make when available.

If vim-dispatch is available, use it in :CrBuild and :CrCompileFile for
asynchronous compilation (in a tmux pane when possible).

BUG=NONE

Review URL: https://codereview.chromium.org/1159593007

Cr-Original-Commit-Position: refs/heads/master@{#333273}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1ff77fd1b198ffa82362851cb43e1efdff068dff
1 file changed