Add 3 scripts to fontset setup

* lisp/international/fontset.el (setup-default-fontset)
(script-representative-chars): Add support for Avestan, Old Turkic
and Chakma.  Patch by Werner Lemberg <wl@gnu.org>.  Do not merge
to master.

lisp/international/fontset.el

@@ -243,6 +243,8 @@
 	(lydian #x10920)
 	(kharoshthi #x10A00)
 	(manichaean #x10AC0)
+	(avestan #x10B00)
+	(old-turkic #x10C00 #x10C01)
 	(hanifi-rohingya #x10D00 #x10D24 #x10D39)
 	(yezidi #x10E80)
 	(old-sogdian #x10F00)
@@ -252,6 +254,7 @@
 	(old-uyghur #x10F70)
         (brahmi #x11013 #x11045 #x11052 #x11065)
         (kaithi #x1108D #x110B0 #x110BD)
+        (chakma #x11103 #x11127)
 	(mahajani #x11150)
         (sharada #x11191 #x111B3 #x111CD)
 	(khojki #x11200)
@@ -832,11 +835,13 @@
                     yezidi
 		    kharoshthi
 		    manichaean
+		    avestan
                     chorasmian
 		    elymaic
                     old-uyghur
                     brahmi
                     kaithi
+                    chakma
                     sharada
                     grantha
                     tirhuta
@@ -852,6 +857,18 @@
 		    pahawh-hmong
 		    medefaidrin
                     znamenny-musical-notation
+                    khudawadi
+                    khojki
+                    mahajani
+                    sogdian
+                    old-sogdian
+                    old-turkic
+                    nabataean
+                    palmyrene
+                    linear-a
+                    linear-b
+                    caucasian-albanian
+                    elbasan
 		    byzantine-musical-symbol
 		    musical-symbol
 		    ancient-greek-musical-notation