Issue #17662: fix socketmodule compilation with Setup.dist.
Patch contributed by Bohuslav "Slavek" Kabrda (bkabrda)
- Issue #13150, #17512: sysconfig no longer parses the Makefile and config.h
  files when imported, instead doing it at build time.  This makes importing
  sysconfig faster and reduces Python startup time by 20%.
Close #17666: Fix reading gzip files with an extra field.
#17657: Show full Tk version in IDLE's about dialog.
Patch by Todd Rovito.