squash! ci : add ccache to build-wasm

More fixes.

Author: danbev

.github/workflows/build-wasm.yml

@@ -54,10 +54,12 @@ jobs:
 
       - name: Build
         env:
-          CCACHE_SLOPPINESS: time_macros
+          CCACHE_SLOPPINESS: time_macros,include_file_mtime,include_file_ctime
           CCACHE_COMPILERCHECK: content
         run: |
           emcmake cmake -B build -DCMAKE_BUILD_TYPE=${{ matrix.build }} \
             -DCMAKE_C_COMPILER_LAUNCHER=ccache \
-            -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+            -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
+            "-DCMAKE_C_FLAGS=-ffile-prefix-map=$EMSDK=/emsdk" \
+            "-DCMAKE_CXX_FLAGS=-ffile-prefix-map=$EMSDK=/emsdk"
           cmake --build build -j $(nproc)