patch 9.0.0271: using INIT() in non-header files

Problem:    Using INIT() in non-header files.
Solution:   Remove INIT(). (closes #10981)
diff --git a/src/gui_xim.c b/src/gui_xim.c
index 4d8706a..d384cbc 100644
--- a/src/gui_xim.c
+++ b/src/gui_xim.c
@@ -154,7 +154,7 @@
 #if defined(FEAT_XIM) || defined(PROTO)
 
 # if defined(FEAT_GUI_GTK) || defined(PROTO)
-static int xim_has_preediting INIT(= FALSE);  // IM current status
+static int xim_has_preediting = FALSE;  // IM current status
 
 /*
  * Set preedit_start_col to the current cursor position.