[Bug middle-end/124509] New: lockfile.cc should have mingw/windows support

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124509

            Bug ID: 124509
           Summary: lockfile.cc should have mingw/windows support
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
              Host: mingw

Currently lockfile.cc does not support windows as it uses fnctl/F_SETLKW.

Windows has its own locking mechanism which should be used:
https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-lockfile
https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-lockfileex