CHANGES: Document Image.{ILBM,X,XWD} fixes

CHANGES

@@ -18,6 +18,11 @@ o Image.GIF
   - Improve detection of malformed LZW bit sizes.
   - Improve detection of malformed LZW dictionary extensions.
 
+o Image.ILBM
+
+  - Guard alloca() allocations with check_c_stack().
+  - Improved length accounting in unpackByteRun1().
+
 o Image.PCX
 
   Improved size checks better detect malformed PCX images.
@@ -44,10 +49,18 @@ o Image.WBF
 
   Improved size check better detects malformed WBF images.
 
+o Image.X
+
+  Guard alloca() allocations with check_c_stack().
+
 o Image.XCF
 
   Fixed to properly initialize the layer mask structure.
 
+o Image.XWD
+
+  Improved size check better detects malformed XWD images.
+
 Building & Tools
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