Revert "Pull and build shaderc rather than use checked in lib/header"

This reverts commit 7d4490ecfa4d974003f675ef004e77f85ecfadd2.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1757253002

Review URL: https://codereview.chromium.org/1757253002 .
7 files changed