Put all prebuild scripts in external files.

Put all prebuild scripts in external files.  Scripts to run unit tests are
staying put for now, because they're all trivial and identical.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=2054

[Mark Mentovai, 2008-09-11 01:42:07]

I'm also turning off the "show environment variables" dump, because we use set
-x which already shows us exactly what we need to see.

I'll need to bump the DEPS to pick up the new ICU project, I'll do that along
with this change once the ICU part is checked in and I have a revision number
for it.

The new scripts are all identical to the old contents of the script phases, with
the exception of a couple of edits to keep things under 80 characters.

The new script phases are parameterized based on environment variables set by
Xcode, so it's just a copy-and-paste job to add a new one.

I'll push the v8 project file change back up to v8 once this goes in.

[Amanda Walker, 2008-09-11 12:54:35]

LGTM