runtime/cgo: merge bodies of cgo_sys_thread_start on windows

The bodies of cgo_sys_thread_start (and x_cgo_sys_thread_create) are
nearly identical on all of the windows ports.

Create a single _cgo_beginthread implementation that contains the body
and is used on all ports. This will reduce churn in an upcoming CL to
add retry logic.

We could theoretically have a single implementation of
_cgo_sys_thread_start shared by all ports, but I keep them separate for
ease of searching. Right now every single port implements this function
in their gcc_GOOS_GOARCH.c file, so it is nice to keep this symmetry.

_cgo_dummy_export must move out of libcgo_windows.h because it is a
definition and the inclusion of libcgo_windows.h in multiple files
creates duplicate definitions.

For #52572.

Change-Id: I9fa22009389349c754210274c7db2631b061f9c7
Run-TryBot: Michael Pratt <>
Reviewed-by: Michael Knyszek <>
Reviewed-by: Ian Lance Taylor <>
TryBot-Result: Gopher Robot <>
5 files changed
tree: 4445bedcddebe01b50acb5803d24b47ccef1f807
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  11. codereview.cfg

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