Bug 1635764 - Move --with-system-icu and --with-intl-api to python configure....
Bug 1635764 - Move --with-system-icu and --with-intl-api to python configure. r=firefox-build-system-reviewers,rstewart At the same time, because it's now simpler to do so, set the right data file name for big-endians, even though we don't have or produce it (bug #1264836). Also remove USE_ICU, which is redundant with JS_HAS_INTL_API, and actively break the build at configure time when using --without-intl-api with Firefox because this hasn't actually worked for close to 3 years (since bug 1402048). Differential Revision: https://phabricator.services.mozilla.com/D77416