Doc'ing unset HOME bugfix for macOS

h/t Mark Kim

(Also, reorganized build stuff)

docs/CHANGES.txt

@@ -134,20 +134,28 @@ http://www.tuxpaint.org/
 
   * Ports & Building:
     -----------------
+    * Windows
       * Windows installer will no nlonger show a dialogue to inform
         user of uninstallation when "/VERYSILENT" switch is specified
         (useful for automated installation/uninsta$llation processes).
         TOYAMA Shin-ichi <shin1@wmail.plala.or.jp>
 
-    * On macOS, use the CMD (⌘) key wherever CTRL is used on other OSes
+    * macOS
       Mark Kim <markuskimius@gmail.com>
 
+      * On macOS, use the CMD (⌘) key wherever CTRL is used on other OSes
+
       * Use character class in macOS build script
         (It appears \t is not compatible with certain versions of grep.)
-      Mark Kim <markuskimius@gmail.com>
 
       * Remove install stages not needed on macOS
-      Mark Kim <markuskimius@gmail.com>
+
+      * When looking up paths of fonts, preferences, etc., macOS searches
+        two places, the system paths and the user paths under $HOME.
+        Now handling rare scenario where HOME is not set; if so,
+        now just searching the system path twice instead of searching the
+        system path followed by going into an undefined behavior
+        (possibly segfault crash).
 
   * Documentation updates:
     ---------------------