cmake: add support for building with Intel C compiler

CMakeLists.txt

@@ -207,7 +207,7 @@ else()
 endif()
 
 # Compiler info
-if(CMAKE_C_COMPILER_ID MATCHES "Clang")
+if(CMAKE_C_COMPILER_ID MATCHES "Clang|IntelLLVM")
   set(USE_CLANG TRUE)
   set(OPT_DEF_ASM TRUE)
   # Visual Studio 2019 v16.2 added support for Clang/LLVM.
@@ -221,11 +221,14 @@ elseif(CMAKE_COMPILER_IS_GNUCC)
 elseif(MSVC_VERSION GREATER 1400) # VisualStudio 8.0+
   set(OPT_DEF_ASM TRUE)
   #set(CMAKE_C_FLAGS "/ZI /WX- /
+elseif(CMAKE_C_COMPILER_ID MATCHES "^Intel$")
+  set(OPT_DEF_ASM TRUE)
+  set(USE_INTELCC TRUE)
 else()
   set(OPT_DEF_ASM FALSE)
 endif()
 
-if(USE_GCC OR USE_CLANG)
+if(USE_GCC OR USE_CLANG OR USE_INTELCC)
   set(OPT_DEF_GCC_ATOMICS ON)
 endif()
 
@@ -551,7 +554,7 @@ if(NOT SDL_FOREGROUNDING_SIGNAL STREQUAL "OFF")
 endif()
 
 # Compiler option evaluation
-if(USE_GCC OR USE_CLANG)
+if(USE_GCC OR USE_CLANG OR USE_INTELCC)
   # Check for -Wall first, so later things can override pieces of it.
   # Note: clang-cl treats -Wall as -Weverything (which is very loud),
   #       /W3 as -Wall, and /W4 as -Wall -Wextra.  So: /W3 is enough.
@@ -689,7 +692,7 @@ if(CMAKE_C_COMPILER_ID STREQUAL "MSVC")
 endif()
 
 if(SDL_ASSEMBLY)
-  if(USE_GCC OR USE_CLANG)
+  if(USE_GCC OR USE_CLANG OR USE_INTELCC)
     # TODO: Those all seem to be quite GCC specific - needs to be
     # reworked for better compiler support
     set(HAVE_ASSEMBLY TRUE)
@@ -2939,7 +2942,7 @@ if(SDL_WERROR)
       set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
       set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /WX")
     endif()
-  elseif(USE_GCC OR USE_CLANG)
+  elseif(USE_GCC OR USE_CLANG OR USE_INTELCC)
     cmake_push_check_state(RESET)
     check_c_compiler_flag(-Werror HAVE_WERROR)
     if(HAVE_WERROR)