build/windows: don't use wrong version number
build/windows: don't use wrong version number

We were using a global temp file while setting the NODE_VERSION
environment variable. This resulted in simultaneous builds swapping
version numbers on occasion.

This patch removes the use of a temp file for this.

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node