I've added more of the ".def" files from mingw. The list is based on all the libraries referenced by the win32metadata project. (see https://github.com/marlersoft/zigwin32).
previously zig would look for all the .defs even when not needed,
wasting time. also, we only had samsrv definitions for some architectures.
remove cross compiling support for this.
also start prefering NtDll API. so far:
* NtQueryInformationFile
* NtClose
adds a performance workaround for windows unicode conversion. but that
should probably be removed before merging
