Explicitly set utf-8 encoding for hyb file verification

Not all platforms default to UTF-8 encoding, so we set it explicitly.
This patch should fix build breakages resulting from failed verification
of binary hyb files for hyphenation patterns.

Bug: 24570591
Change-Id: I65ac4536d3436586c2633e2b57554fc6ff16d3a8
(cherry picked from commit 179d763488)

engine/src/flutter/tools/mk_hyb_file.py

@@ -416,7 +416,7 @@ def generate_hyb_file(hyph, ch_map, hyb_fn):
 
 # Verify that the file contains the same lines as the lines argument, in arbitrary order
 def verify_file_sorted(lines, fn):
-    file_lines = [l.strip() for l in io.open(fn)]
+    file_lines = [l.strip() for l in io.open(fn, encoding='UTF-8')]
     line_set = set(lines)
     file_set = set(file_lines)
     if line_set == file_set: