Cygwin: Reproduce the AArch64 toolchain build from #125

[Blackhex]

Description

• Checkout branch of Add aarch64-pc-cygwin target to advanced.yml #123 on either Linux AArch64 machine or Windows Arm64 machine with WSL running Ubuntu 22.04.
• (if appliable) Rebase it to the current main branch and resolve all build script and GitHub Actions workflow files regressions.
• Run .github/scripts/build.sh build script.
• The build procedure will most probably fail on applying patches to the upstream GCC, binutils, MinGW, or Cygwin repositories as they diverged over the time.
• Try to fix as many code compatibility regressions as possible so that the build script will succeed.

Notes

• You might decide or need to update the Cygwin patches repository https://github.com/Windows-on-ARM-Experiments/cygwin-packages formed by several git submodules links to other repositories where the actual patches are placed:
  • binutils, cygwin, gettext, and libiconv link to the upstream repositories directly - updating the submodule link is enough.
  • gcc links to https://github.com/Windows-on-ARM-Experiments/cygwin-gcc-package - that repository needs to be rebased to the upstream first, then the submodule link can be updated.  

Acceptance Criteria

• The Add aarch64-pc-cygwin target to advanced.yml #123 PR branch (aarch64-cygwin) is rebased to the main branch of this repository.
• The .github/scripts/build.sh build script passes on AArch64 Ubuntu 22.04 (or WSL) or all issue preventing the build has been identified, reported as tickets in this repository and linked to this ticket.

[eukarpov]

Achieving the goal of building the Cygwin toolchain and being able to compile an executable.

~/cross-aarch64-pc-cygwin-msvcrt/bin/aarch64-pc-cygwin-gcc test.c
 
Dump of file a.exe
 
File Type: EXECUTABLE IMAGE
 
  Image has the following dependencies:
 
    cygwin1.dll
    KERNEL32.dll

Getting the "Hello Cygwin" application working is the main priority.
It will help define the scope of required changes in the toolchain build.
Here are the work-in-progress branches that might help build the Cygwin toolchain.

mingw-woarm64-build: aarch64-cygwin-wip
binutils: aarch64-cygwin-wip
gcc: aarch64-cygwin-wip
mingw: aarch64-cygwin-wip
newlib-cygwin: aarch64-cygwin-wip