Xcode: Fix build failure when linking to an external static library whose path is not relative. Static libraries (i.e., .a files) are translated into a -l<name> flag, so a corresponding -L is needed no matter what the format of the path is.
Xcode: Fix build failure when linking to an external static library whose path
is not relative. Static libraries (i.e., .a files) are translated into a
-l<name> flag, so a corresponding -L is needed no matter what the format of
the path is.

Patch by Tristan Schmelcher <tschmelcher@chromium.org>

TEST=built O3D with the change and verified linking to external static
     libraries works; gyptest.py -a
BUG=none

old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google