[M106] Make references to //third_party/icu relative

Original change:
https://chromium.googlesource.com/chromium/deps/icu/+/20f8ac695af59b6c830def7d4e95bfeb13dd7be5

This allows the build of ICU to be placed in directories other
than //third_party/icu downstream.

The change does not make a difference in code bases that
continue to use //third_party/icu.

Bug: fuchsia:108544
Change-Id: I9f9c99e9d2bfa31dfc64e181c8cf60816d5164cc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/3913866
Reviewed-by: Frank Tang <ftang@chromium.org>
1 file changed