Upstream commit dddccbc3ef50ac52bf00723fd2f68d98140aab80
* adds ucrtbase.def.in
* mingwex: replace mingw crt files with ucrt files
* adds missing mingw-w64 ucrt files
The rules that govern which set of files are included or excluded is
contained in the logic for tools/update_mingw.zig
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
