This is such a simple one-line fix that I'm gonna try mentioning it here instead of forking and pulling.
In the windows build script there this line 23:
if (%2)==(cl) set CC=@call :cl
But this assumes that the Microsoft c compiler is called "cl" when it's officially "CL", so in case the user types the name in upper case, the test should be case-insensitive (which the windows command line is). So it should be:
if /I (%2)==(cl) set CC=@call :cl
In case you have a sans serif font, that's an upper case i not a lower case L after the slash.
If line 23 fails when it should succeed, then CL is asked to link against tcc.dll, but that compiler wants to be told to link against a lib file, even if the target of that lib file is a dll. With the "call" in there, it does the right thing.