CI for Packages on Windows & Android?

Okay, this is the script for Android. I would be happy to fix anything that looks wrong to those of you smarter than I.

Workaround Notes:

  1. SwiftPM isn’t in the cross‐compilation toolchain, so two toolchains are needed at once.
  2. SwiftPM must be ≤ 5.1.1; newer releases suffer from SR‐12123.
  3. libswiftSwiftOnoneSupport.so and libswiftGlibc.so need linkage adjustments. (See earlier posts.)
  4. SwiftPM insists on the wrong --sysroot, so the contents of the real sysroot need to be copyied to where it points.
  5. libicudt64.so needs to be acquired separately.
  6. (I haven’t bothered with FoundationNetworking or FoundationXML yet; they have additional dependencies.)