[mono][wasm] Small cleanups (#77954)

* [mono][wasm] Pass -DEMSCRIPTEN_SYSTEM_PROCESSOR=wasm to cmake so Emscripten.cmake doesn't set CMAKE_SYSTEM_PROCESSOR to x86.

* [mono][wasm] Fix the hello world sample.

Author: vargaz

src/mono/CMakeLists.txt

@@ -358,11 +358,6 @@ if(NOT "${MSVC_C_ARCHITECTURE_ID}" STREQUAL "")
   set(CMAKE_SYSTEM_PROCESSOR "${MSVC_C_ARCHITECTURE_ID}")
 endif()
 
-if(HOST_BROWSER)
-  # CMAKE_SYSTEM_PROCESSOR is set to x86 by emscripten
-  set(CMAKE_SYSTEM_PROCESSOR "wasm")
-endif()
-
 # Unify naming
 if(CMAKE_SYSTEM_PROCESSOR STREQUAL "armv7l" OR CMAKE_SYSTEM_PROCESSOR STREQUAL "ARMV7")
   set(CMAKE_SYSTEM_PROCESSOR "arm")

src/mono/mono.proj

@@ -351,6 +351,7 @@
       <_MonoCMakeArgs Include="-DENABLE_ICALL_EXPORT=1"/>
       <_MonoCMakeArgs Include="-DENABLE_LAZY_GC_THREAD_CREATION=1"/>
       <_MonoCMakeArgs Include="-DENABLE_LLVM_RUNTIME=1"/>
+      <_MonoCMakeArgs Include="-DEMSCRIPTEN_SYSTEM_PROCESSOR=wasm"/>
       <_MonoCFLAGS Include="-fexceptions"/>
       <_MonoCFLAGS Condition="'$(MonoWasmThreads)' == 'true'" Include="-pthread"/>
       <_MonoCFLAGS Condition="'$(MonoWasmThreads)' == 'true'" Include="-D_GNU_SOURCE=1" />