Update compiler target for wasi-threads examples

The target was updated to wasm32-wasi-threads in wasi-libc (and most likely will stay like that for a while)
WebAssembly/wasi-libc#381

Author: loganek

samples/wasi-threads/wasm-apps/CMakeLists.txt

@@ -14,7 +14,7 @@ endif ()
 set (CMAKE_SYSROOT                  "${WASI_SYSROOT}")
 set (CMAKE_C_COMPILER               "${WASI_SDK_DIR}/bin/clang")
 set (CMAKE_ASM_COMPILER               "${WASI_SDK_DIR}/bin/clang")
-set (CMAKE_C_COMPILER_TARGET        "wasm32-wasi")
+set (CMAKE_C_COMPILER_TARGET        "wasm32-wasi-threads")
 
 function (compile_sample SOURCE_FILE)
   get_filename_component (FILE_NAME ${SOURCE_FILE} NAME_WLE)