I'm able to build Linux executables just fine using Bash for Windows but, I can't seem to figure out how to build executables that can run on Windows.

I'm not sure what those errors above mean but, I had a lot of trouble running any script until I realized the issue was related to extra CR (or LF) characters added by Windows to all these files that I obtained using Git for Windows.  To solve this, I deleted the project that I cloned using Windows and used Git on the Bash environment itself to obtain a fresh copy of the bitcoin 0.13 project.