cmake: Deprecate legacy CMake for all platforms

We now support the new, modern CMake path on all platforms. Encourage
everyone to migrate by deprecating the legacy CMake path. The legacy
CMake path will be removed in a future update.

CMakeLists.txt

@@ -34,21 +34,19 @@ if(CMAKE_HOST_SYSTEM_NAME MATCHES "(Darwin)" OR OBS_CMAKE_VERSION VERSION_GREATE
   return()
 endif()
 
-if(CMAKE_HOST_SYSTEM_NAME MATCHES "(Windows|Darwin)")
-  message(
-    DEPRECATION
-      "\n"
-      "============ LEGACY BUILD SYSTEM IS DEPRECATED ============"
-      "\n"
-      "You are using the legacy build system to build OBS Studio. "
-      "The legacy build system is unsupported and will be removed in the near future."
-      "\n"
-      "To migrate to the new build system, familiarize yourself with CMake presets "
-      "(https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html) and create "
-      "a user preset with your customized build settings, inheriting from one of the default presets."
-      "\n"
-      "============ LEGACY BUILD SYSTEM IS DEPRECATED ============")
-endif()
+message(
+  DEPRECATION
+    "\n"
+    "============ LEGACY BUILD SYSTEM IS DEPRECATED ============"
+    "\n"
+    "You are using the legacy build system to build OBS Studio. "
+    "The legacy build system is unsupported and will be removed in the near future."
+    "\n"
+    "To migrate to the new build system, familiarize yourself with CMake presets "
+    "(https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html) and create "
+    "a user preset with your customized build settings, inheriting from one of the default presets."
+    "\n"
+    "============ LEGACY BUILD SYSTEM IS DEPRECATED ============")
 
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake/Modules")
 include(VersionConfig)