Don't pass `-exhaustive-register-search` directly to clang compiler

`-exhaustive-register-search` is an LLVM code generation flag that shouldn't be passed directly to clang compiler.

cmake/system.cmake

@@ -172,9 +172,9 @@ if (DEFINED TARGET)
         endif()
     elseif (${CMAKE_C_COMPILER_ID} STREQUAL "Clang" OR ${CMAKE_C_COMPILER_ID} STREQUAL "AppleClang")
          if (${CMAKE_C_COMPILER_VERSION} VERSION_GREATER 8.99)
-          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=cooperlake -exhaustive-register-search")
+          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=cooperlake -mllvm -exhaustive-register-search")
         else()
-          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512 -exhaustive-register-search")
+          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512 -mllvm -exhaustive-register-search")
         endif()
     endif()    
   endif()
@@ -188,16 +188,16 @@ if (DEFINED TARGET)
         endif()
     elseif (${CMAKE_C_COMPILER_ID} STREQUAL "Clang" OR ${CMAKE_C_COMPILER_ID} STREQUAL "AppleClang")
          if (${CMAKE_C_COMPILER_VERSION} VERSION_GREATER 12.0)
-          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=sapphirerapids -exhaustive-register-search")
+          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=sapphirerapids -mllvm -exhaustive-register-search")
         else()
-          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512 -exhaustive-register-search")
+          set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512 -mllvm -exhaustive-register-search")
         endif()
     endif()    
   endif()
   if (${TARGET} STREQUAL SKYLAKEX AND NOT NO_AVX512)
     	  set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512")
   	  if (${CMAKE_C_COMPILER_ID} STREQUAL "Clang" OR ${CMAKE_C_COMPILER_ID} STREQUAL "AppleClang")
-	 	set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -exhaustive-register-search")
+	 	set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -mllvm -exhaustive-register-search")
   	  endif()
   endif()
   
@@ -215,7 +215,7 @@ if (DEFINED TARGET)
 	else()
     	  set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -march=skylake-avx512")
         endif()
-	set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -exhaustive-register-search")
+	set (KERNEL_DEFINITIONS "${KERNEL_DEFINITIONS} -mllvm -exhaustive-register-search")
     endif()
   endif()