Remove redundant bug fix, add graphite dependencies

Lib/fontTools/ttLib/sfnt.py

@@ -556,7 +556,6 @@ def calcChecksum(data):
 		3655064932
 	"""
 	remainder = len(data) % 4
-	data = data[:]          # py3 data is a bytearray so copy it before modifying
 	if remainder:
 		data += b"\0" * (4 - remainder)
 	value = 0

Lib/fontTools/ttLib/tables/G__l_a_t.py

@@ -141,8 +141,8 @@ class table_G__l_a_t(DefaultTable.DefaultTable):
     def compileAttributes12(self, attrs, fmt):
         data = b""
         for e in grUtils.entries(attrs):
-            data += sstruct.pack(fmt, {'attNum' : e[0], 'num' : e[1]})
-            data += struct.pack(('>%dh' % len(e[2])), *e[2])
+            data += sstruct.pack(fmt, {'attNum' : e[0], 'num' : e[1]}) + \
+                    struct.pack(('>%dh' % len(e[2])), *e[2])
         return data
     
     def compileAttributes3(self, attrs):

setup.py

@@ -58,6 +58,10 @@ extras_require = {
 			"python_version < '3.7' and platform_python_implementation != 'PyPy'"
 		),
 	],
+	# for graphite type tables in ttLib/tables (Silf, Glat, Gloc)
+	"graphite": [
+		"lz4 >= 1.7.4.2"
+	],
 	# for fontTools.interpolatable: to solve the "minimum weight perfect
 	# matching problem in bipartite graphs" (aka Assignment problem)
 	"interpolatable": [