Don't assume underlined symbols for ifx; make cpuid.S inclusion conditional

cmake/prebuild.cmake

@@ -58,7 +58,7 @@ set(TARGET_CONF_TEMP "${PROJECT_BINARY_DIR}/${TARGET_CONF}.tmp")
 
 # c_check
 set(FU "")
-if (APPLE OR (MSVC AND NOT ${CMAKE_C_COMPILER_ID} MATCHES "Clang"))
+if (APPLE OR (MSVC AND NOT (${CMAKE_C_COMPILER_ID} MATCHES "Clang" OR ${CMAKE_C_COMPILER_ID} MATCHES "IntelLLVM")))
   set(FU "_")
 endif()
 if(MINGW AND NOT MINGW64)
@@ -1433,7 +1433,9 @@ else(NOT CMAKE_CROSSCOMPILING)
     message(STATUS "MSVC")
     set(GETARCH_FLAGS ${GETARCH_FLAGS} -DFORCE_GENERIC)
   else()
-    list(APPEND GETARCH_SRC ${PROJECT_SOURCE_DIR}/cpuid.S)
+    if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
+      list(APPEND GETARCH_SRC ${PROJECT_SOURCE_DIR}/cpuid.S)
+    endif()
     if (DEFINED TARGET_CORE)
     set(GETARCH_FLAGS ${GETARCH_FLAGS} -DFORCE_${TARGET_CORE})
   endif ()