[cmake] Unreviewed, add definitions necessary to use ICU shipped with macOS

   [cmake] Unreviewed, add definitions necessary to use ICU shipped with macOS

       macOS system ICU libraries are built with U_DISABLE_RENAMING=1 and
       U_SHOW_CPLUSPLUS_API=0. After r219155 we have to pass this definitons
       explicitly, because ICU headers in the tree are not modified anymore.

.:

* Source/cmake/OptionsJSCOnly.cmake:
* Source/cmake/OptionsMac.cmake:

Source/WTF:

* wtf/PlatformMac.cmake: Rely on ICU_LIBRARIES instead of passing ICU
library name explicitly in WTF_LIBRARIES.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@219724 268f45cc-cd09-0410-ab3c-d52691b4dbfc