For command line (i.e. - makefile) users only:
You (like me) probably "tuned" your makefile to #1, above, via something like this:
MS_SDK_BASE_DOS := C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A
ENV_SET := LIB="$(MS_SDK_BASE_DOS)\Lib\x64"
But, now, you need to change that tuning to #2, above, like this:
MS_SDK_BASE_DOS := C:\Program Files\Microsoft SDKs\Windows\v7.1
(Don't miss the "v7.0A" to "v7.1" change, as well.)