ci: extract D:/a/_temp/msys64/clang64 to a variable

Author: elopez

.github/scripts/windows-ghc-toolchain.cmake

@@ -3,8 +3,8 @@ set(CMAKE_SYSTEM_NAME Windows)
 set(CMAKE_C_COMPILER "$ENV{HASKELL_MINGW_PATH}/bin/cc.exe")
 set(CMAKE_CXX_COMPILER "$ENV{HASKELL_MINGW_PATH}/bin/c++.exe")
 
-set(CMAKE_C_FLAGS "-idirafter D:/a/_temp/msys64/clang64/include")
-set(CMAKE_CXX_FLAGS "-idirafter D:/a/_temp/msys64/clang64/include")
+set(CMAKE_C_FLAGS "-idirafter $ENV{SYSTEM_MINGW_PATH}/include")
+set(CMAKE_CXX_FLAGS "-idirafter $ENV{SYSTEM_MINGW_PATH}/include")
 
 set(CMAKE_FIND_ROOT_PATH "$ENV{HASKELL_MINGW_PATH}")
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM BOTH)

.github/workflows/build.yml

@@ -159,12 +159,13 @@ jobs:
       - name: Configure the build
         run: |
           export PATH="$HASKELL_PATHS:$PATH"
+          export SYSTEM_MINGW_PATH="D:/a/_temp/msys64/clang64"
           cabal configure --disable-documentation --enable-executable-static --enable-executable-stripping \
             --extra-lib-dirs="$(cygpath -m "$HASKELL_MINGW_PATH/x86_64-w64-mingw32/lib")" \
             --extra-lib-dirs="$(cygpath -m "$HASKELL_MINGW_PATH/lib")" \
-            --extra-lib-dirs="D:/a/_temp/msys64/clang64/lib" \
+            --extra-lib-dirs="$SYSTEM_MINGW_PATH/lib" \
             --extra-include-dirs="$HOME/.local/include" --extra-lib-dirs="$HOME/.local/lib" \
-            --ghc-options=-pgml="$(cygpath -m "$HASKELL_MINGW_PATH/bin/clang.exe") -optc-idirafter -optcD:/a/_temp/msys64/clang64/include -optcxx-idirafter -optcxxD:/a/_temp/msys64/clang64/include" -fstatic-secp256k1 --constraint="zlib +bundled-c-zlib"
+            --ghc-options=-pgml="$(cygpath -m "$HASKELL_MINGW_PATH/bin/clang.exe") -optc-idirafter -optc$SYSTEM_MINGW_PATH/include -optcxx-idirafter -optcxx$SYSTEM_MINGW_PATH/include" -fstatic-secp256k1 --constraint="zlib +bundled-c-zlib"
           cabal build --dry-run
           # The last step generates dist-newstyle/cache/plan.json for the cache key.