Disable wgpu on linux (#5186)

* remove setting CMAKE_SYSTEM_PROCESSOR

we will need a proper toolchain file to setup cross-compilation

* disable slang-rhi webgpu backend on linux

this is a temporary fix for allowing the release workflow to run

.github/workflows/release.yml

@@ -71,13 +71,11 @@ jobs:
             export CC=aarch64-linux-gnu-gcc
             export CXX=aarch64-linux-gnu-g++
           fi
-          CMAKE_SYSTEM_PROCESSOR="${{matrix.platform}}"
           CMAKE_OSX_ARCHITECTURES="${{matrix.platform}}"
           CMAKE_OSX_ARCHITECTURES=${CMAKE_OSX_ARCHITECTURES//aarch64/arm64}
 
           echo "CC=$CC" >> "$GITHUB_ENV"
           echo "CXX=$CXX" >> "$GITHUB_ENV"
-          echo "CMAKE_SYSTEM_PROCESSOR=$CMAKE_SYSTEM_PROCESSOR" >> "$GITHUB_ENV"
           echo "CMAKE_OSX_ARCHITECTURES=$CMAKE_OSX_ARCHITECTURES" >> "$GITHUB_ENV"
 
       - name: Build Slang

external/CMakeLists.txt

@@ -71,6 +71,9 @@ set(SLANG_RHI_BINARY_DIR ${CMAKE_BINARY_DIR}/$<CONFIG>/bin)
 set(SLANG_RHI_SLANG_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/include)
 set(SLANG_RHI_SLANG_BINARY_DIR ${CMAKE_BINARY_DIR})
 set(SLANG_RHI_BUILD_TESTS OFF)
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    set(SLANG_RHI_ENABLE_WGPU OFF)
+endif()
 if(SLANG_ENABLE_DX_ON_VK)
     set(SLANG_RHI_HAS_D3D12 ON)
 endif()