hardcode icu output prefix

Author: nektro

Dockerfile.musl

@@ -54,7 +54,7 @@ RUN --mount=type=tmpfs,target=/icu \
     tar -xf /icu.tgz --strip-components=1 && \
     rm /icu.tgz && \
     cd source && \
-    ./configure  --enable-static --disable-shared --with-data-packaging=static --disable-samples --disable-debug --disable-tests && \
+    ./configure  --enable-static --disable-shared --with-data-packaging=static --disable-samples --disable-debug --disable-tests --prefix=/icu && \
     make -j$(nproc) && \
     make install && cp -r /icu/source/lib/* /output/lib && cp -r /icu/source/i18n/unicode/* /icu/source/common/unicode/* /output/include/unicode