[meson] disable icu for amalgam build on CI for now

Causes linking errors

test-unicode.c:960: undefined reference to `hb_icu_get_unicode_funcs'
test-unicode.c:961: undefined reference to `hb_icu_get_unicode_funcs'

Need to have a separate harfbuzz-icu module and link against that,
and/or generate harfbuzz.cc.

.circleci/config.yml

@@ -232,8 +232,8 @@ jobs:
       - run: apt update && apt install -y ninja-build binutils meson gcc g++ pkg-config ragel gtk-doc-tools libfreetype6-dev libglib2.0-dev libcairo2-dev libicu-dev libgraphite2-dev python python-pip
       - run: pip install fonttools
       - run: meson build && ninja -Cbuild test && rm -rf build
-      # test amalgam build
-      - run: meson build -Damalgam=true && ninja -Cbuild && rm -rf build
+      # test amalgam build (FIXME: enable icu again)
+      - run: meson build -Dicu=disabled -Damalgam=true && ninja -Cbuild && rm -rf build
       # test meson's own unity feature also
       - run: meson build --unity on && ninja -Cbuild && rm -rf build