Fix compatibility problem with CMake policy CMP0025 (#2277)

Signed-off-by: Qingyao Sun <[email protected]>

docs/CONTRIBUTORS

@@ -33,6 +33,7 @@ Patrick Stewart
 Peter Monsson
 Philipp Wagner
 Pieter Kapsenberg
+Qingyao Sun
 Richard Myers
 Sean Cross
 Sebastien Van Cauwenberghe

verilator-config.cmake.in

@@ -163,7 +163,9 @@ function(verilate TARGET)
   endforeach()
 
   string(TOLOWER ${CMAKE_CXX_COMPILER_ID} COMPILER)
-  if (NOT COMPILER MATCHES "msvc|clang")
+  if (COMPILER STREQUAL "appleclang")
+    set(COMPILER clang)
+  elseif (NOT COMPILER MATCHES "^msvc$|^clang$")
     set(COMPILER gcc)
   endif()