Cleanup: set WITH_INPUT_IME=OFF when unsupported

This avoids having to do platform checks before checking WITH_INPUT_IME.

CMakeLists.txt

@@ -513,6 +513,8 @@ endif()
 # Misc
 if(WIN32 OR APPLE)
   option(WITH_INPUT_IME "Enable Input Method Editor (IME) for complex Asian character input" ON)
+else()
+  set(WITH_INPUT_IME OFF)
 endif()
 option(WITH_INPUT_NDOF "Enable NDOF input devices (SpaceNavigator and friends)" ON)
 if(UNIX AND NOT APPLE)
@@ -1138,7 +1140,7 @@ if(UNIX AND NOT (APPLE OR HAIKU))
 endif()
 set_and_warn_incompatible(WITH_HEADLESS WITH_GHOST_SDL OFF)
 
-if(WIN32 OR APPLE)
+if(WITH_INPUT_IME)
   set_and_warn_incompatible(WITH_HEADLESS WITH_INPUT_IME OFF)
   set_and_warn_incompatible(WITH_GHOST_SDL WITH_INPUT_IME OFF)
 endif()

source/blender/blentranslation/CMakeLists.txt

@@ -42,10 +42,8 @@ if(WITH_PYTHON)
   )
 endif()
 
-if(WIN32 OR APPLE)
-  if(WITH_INPUT_IME)
-    add_definitions(-DWITH_INPUT_IME)
-  endif()
+if(WITH_INPUT_IME)
+  add_definitions(-DWITH_INPUT_IME)
 endif()
 
 blender_add_lib(bf_blentranslation "${SRC}" "${INC}" "${INC_SYS}" "${LIB}")

source/blender/editors/interface/CMakeLists.txt

@@ -117,10 +117,8 @@ if(WITH_PYTHON)
   add_definitions(-DWITH_PYTHON)
 endif()
 
-if(WIN32 OR APPLE)
-  if(WITH_INPUT_IME)
-    add_definitions(-DWITH_INPUT_IME)
-  endif()
+if(WITH_INPUT_IME)
+  add_definitions(-DWITH_INPUT_IME)
 endif()
 
 if(WITH_EXPERIMENTAL_FEATURES)

source/blender/windowmanager/CMakeLists.txt

@@ -175,10 +175,8 @@ if(WITH_INPUT_NDOF)
   add_definitions(-DWITH_INPUT_NDOF)
 endif()
 
-if(WIN32 OR APPLE)
-  if(WITH_INPUT_IME)
-    add_definitions(-DWITH_INPUT_IME)
-  endif()
+if(WITH_INPUT_IME)
+  add_definitions(-DWITH_INPUT_IME)
 endif()
 
 if(WITH_COMPOSITOR_CPU)