Fix a Python3 compatibility issue in asm_to_inline_asm.py.

I tripped over this str/bytes issue as part of bringing up the
Chromium build under Python3.

Bug: chromium:1112471
Change-Id: I723c7d9df8bcac24c160c549a03dcbd34c1d92f6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2334222
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69210}

tools/snapshot/asm_to_inline_asm.py

@@ -15,12 +15,12 @@ import sys
 
 def asm_to_inl_asm(in_filename, out_filename):
   with open(in_filename, 'r') as infile, open(out_filename, 'wb') as outfile:
-    outfile.write('__asm__(\n')
+    outfile.write(b'__asm__(\n')
     for line in infile:
       # Escape " in .S file before outputing it to inline asm file.
       line = line.replace('"', '\\"')
-      outfile.write('  "%s\\n"\n' % line.rstrip())
-    outfile.write(');\n')
+      outfile.write(b'  "%s\\n"\n' % line.rstrip().encode('utf8'))
+    outfile.write(b');\n')
   return 0
 
 if __name__ == '__main__':