This commit introduces tools/update_glibc.zig to update the start files
for next time.
Some notable changes in recent glibc:
* abi-note.S has been changed to abi-note.c but we resist the change to
keep it easier to compile the start files.
* elf-init.c has been deleted upstream. Further testing should be done
to verify that binaries against glibc omitting elf-init.c still run
properly on oldel glibc linux systems.
Closes#4926
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
