Force clang as CMake Assembly compiler, with wasm32-wasi triple (#315)

Sometimes a C codebase might have the odd file written in Assembly. We should force the use of Clang as the assembly compiler for these cases (which it is perfectly capable of doing), and make sure we pass on the WASI compiler triple the same way we do for C and C++.

wasi-sdk-pthread.cmake

@@ -18,10 +18,12 @@ endif()
 
 set(CMAKE_C_COMPILER ${WASI_SDK_PREFIX}/bin/clang${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_CXX_COMPILER ${WASI_SDK_PREFIX}/bin/clang++${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_ASM_COMPILER ${WASI_SDK_PREFIX}/bin/clang${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_AR ${WASI_SDK_PREFIX}/bin/llvm-ar${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_RANLIB ${WASI_SDK_PREFIX}/bin/llvm-ranlib${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_C_COMPILER_TARGET ${triple})
 set(CMAKE_CXX_COMPILER_TARGET ${triple})
+set(CMAKE_ASM_COMPILER_TARGET ${triple})
 
 # Don't look in the sysroot for executables to run during the build
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)

wasi-sdk.cmake

@@ -16,10 +16,12 @@ endif()
 
 set(CMAKE_C_COMPILER ${WASI_SDK_PREFIX}/bin/clang${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_CXX_COMPILER ${WASI_SDK_PREFIX}/bin/clang++${WASI_HOST_EXE_SUFFIX})
+set(CMAKE_ASM_COMPILER ${WASI_SDK_PREFIX}/bin/clang${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_AR ${WASI_SDK_PREFIX}/bin/llvm-ar${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_RANLIB ${WASI_SDK_PREFIX}/bin/llvm-ranlib${WASI_HOST_EXE_SUFFIX})
 set(CMAKE_C_COMPILER_TARGET ${triple})
 set(CMAKE_CXX_COMPILER_TARGET ${triple})
+set(CMAKE_ASM_COMPILER_TARGET ${triple})
 
 # Don't look in the sysroot for executables to run during the build
 set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)