Revert "Add flag for compiling into shared libraries." This reverts commit eb405d8a422eb77910a15715d17b60b7f10bbf8c. Reason for revert: because we plan to compile icu into static library. BUG=chromium:1020393 Change-Id: I49d3ff3d44217c3cea1bd9ce44e11db774395d44 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/2065689 Reviewed-by: Jungshik Shin <jshin@chromium.org>