cmake: use option to pass extra check options instead of hardcoding them

.github/workflows/vmactions.yml

@@ -44,5 +44,7 @@ jobs:
               libudev-devd
 
         run: |
-          cmake -S . -B build -GNinja
+          cmake -S . -B build -GNinja \
+            -DSDL_EXTRA_CHECK_INCLUDES="/usr/local/include" \
+            -DSDL_EXTRA_CHECK_LINK_OPTIONS="-L/usr/local/lib"
           cmake --build build --verbose -- -j`sysctl -n hw.ncpu`

CMakeLists.txt

@@ -203,10 +203,12 @@ elseif(NINTENDO_3DS)
   set(N3DS TRUE)
 endif()
 
-if(FREEBSD OR NETBSD OR OPENBSD OR BSDI)
-  list(APPEND CMAKE_REQUIRED_INCLUDES /usr/local/include)
-  list(APPEND CMAKE_REQUIRED_LINK_OPTIONS "-L/usr/local/lib")
-endif()
+set(SDL_EXTRA_CHECK_INCLUDES "" CACHE STRING "Extra includes (for CMAKE_REQUIRED_INCLUDES)")
+set(SDL_EXTRA_CHECK_LINK_OPTIONS "" CACHE STRING "Extra link options (for CMAKE_REQUIRED_LINK_OPTIONS)")
+mark_as_advanced(SDL_EXTRA_CHECK_INCLUDES SDL_EXTRA_CHECK_LINK_OPTIONS)
+
+list(APPEND CMAKE_REQUIRED_INCLUDES ${SDL_CHECK_REQUIRED_INCLUDES})
+list(APPEND CMAKE_REQUIRED_LINK_OPTIONS ${SDL_CHECK_REQUIRED_LINK_OPTIONS})
 
 # Don't mistake osx for unix
 if(UNIX AND NOT ANDROID AND NOT APPLE AND NOT RISCOS)