makensis exit code not checked on Windows

[FaustinCarter]

In verbose mode the makensis return code is not properly checked. Any failure of makensis will be treated as a success by constructor. This is because subprocess.Popen.communicate (line 209) does note raise an error for non-zero return codes the same way that subprocess.check_call (line 217) does.

https://github.com/conda/constructor/blob/a7ad3d2807129b2cdc596337b5081df1967002d5/constructor/winexe.py#L207-L220

Suggested fix is to explicitly check sub.returncode and raise an error.