autotools.bbclass: Add glibc-site to deps

autotools.bbclass: Add glibc-site to deps

This can reduce configure time, here is a test result:

$ bitbake recipe -cconfigure && bitbake recipe -ccleansstate && time bitbake recipe -cconfigure
- gettext:
    before: 2m38.382s
    after: 2m33.099s

- coreutils:
    before: 1m19.967s
    after: 1m13.574s

- bison:
    before: 0m56.203s
    after: 0m50.134s

But there is nearly no difference when bitbake core-image-minimal or
core-image-sato, I think it is because glibc-site requires about 30s to build,
and these recipes depend on it, so there is no difference when do large builds.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>