Revert of win 2015: Update the toolchain package to VS2015 RTM.

build/vs_toolchain.py

Index: build/vs_toolchain.py
diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index 25131659f795588f3156c48b0150890aad2f9c48..16f447755656bb5427097660553f8af28f8d74f0 100644
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -186,8 +186,10 @@
 def _GetDesiredVsToolchainHashes():
   """Load a list of SHA1s corresponding to the toolchains that we want installed
   to build with."""
+  # TODO(scottmg): If explicitly set to VS2015 override hashes to the VS2015 RC
+  # toolchain. http://crbug.com/492774.
   if os.environ.get('GYP_MSVS_VERSION') == '2015':
-    return ['49ae4b60d898182fc3f521c2fcda82c453915011']
+    return ['40721575c85171cea5d7afe5ec17bd108a94796e']
   else:
     # Default to VS2013.
     return ['ee7d718ec60c2dc5d255bbe325909c2021a7efef']