Fix Windows ROCm CMake HIP detection

- Add HIP_DIR to CMAKE_PREFIX_PATH for CMake to find hip-config.cmake
- Set CMAKE_HIP_COMPILER explicitly to extracted clang.exe
- Set HIP_PATH and HIP_DIR cmake variables for proper HIP package discovery

Author: superm1

.github/workflows/build.yml

@@ -93,14 +93,17 @@ jobs:
         run: |
           mkdir build
           cd build
-          $env:CMAKE_PREFIX_PATH="${env:HIP_PATH}"
+          $env:CMAKE_PREFIX_PATH="${env:HIP_PATH};${env:HIP_PATH}\lib\cmake\hip"
           cmake .. `
             -G "Unix Makefiles" `
             -DSD_HIPBLAS=ON `
             -DSD_BUILD_SHARED_LIBS=ON `
             -DGGML_NATIVE=OFF `
             -DCMAKE_C_COMPILER=clang `
             -DCMAKE_CXX_COMPILER=clang++ `
+            -DCMAKE_HIP_COMPILER="${env:HIP_PATH}\bin\clang.exe" `
+            -DHIP_PATH="${env:HIP_PATH}" `
+            -DHIP_DIR="${env:HIP_PATH}\lib\cmake\hip" `
             -DCMAKE_BUILD_TYPE=Release `
             -DGPU_TARGETS="${{ env.GPU_TARGETS }}"
           cmake --build . --config Release --parallel ${env:NUMBER_OF_PROCESSORS}