stopgap solution: add patch for freetype/harfbuzz: do not use pkgconf to locate icu

This is necessary when icu is not built locally, because the pkgconf paths baked for icu will most likely not match the local paths. Pkgconf seems to prefer system include directories over our shared install directory, so if libicu-dev is installed, it will be used instead, and the build breaks. Credit to dmitryk for suggesting this stopgap solution and debugging this rabbit hole with me. A better long-term solution might be to re-run pkgconfig to fix these paths to match the local system.