Update V8 to r7079 as required by WebKit r80534.

Change-Id: I487c152e485d5a40b68997d7c0d2f1fba5da0834
diff --git a/tools/utils.py b/tools/utils.py
index 8083091..fb94d14 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -49,6 +49,8 @@
     return 'linux'
   elif id == 'Darwin':
     return 'macos'
+  elif id.find('CYGWIN') >= 0:
+    return 'cygwin'
   elif id == 'Windows' or id == 'Microsoft':
     # On Windows Vista platform.system() can return 'Microsoft' with some
     # versions of Python, see http://bugs.python.org/issue1082