This patch aims to cleanup the use of `process.h` header and the macro
`HAVE_PROCESS_H` associated with it.
- `process.h` is always available on Windows. In curl, it is required
only for `_beginthreadex()` in `lib/curl_threads.c`.
- `process.h` is also available in MS-DOS. In curl, its only use was in
`lib/smb.c` for `getpid()`. But `getpid()` is in fact declared by
`unistd.h`, which is always enabled via `lib/config-dos.h`. So the
header is not necessary.
- `HAVE_PROCESS_H` was detected by CMake, forced to 1 on Windows and
left to real detection for other platforms.
It was also set to always-on in `lib/config-win32.h` and
`lib/config-dos.h`.
In autotools builds, there was no detection and the macro was never
set.
Based on these observations, in this patch we:
- Rework Windows `getpid` logic in `lib/smb.c` to always use the
equivalent direct Win32 API function `GetCurrentProcessId()`, as we
already did for Windows UWP apps. This makes `process.h` unnecessary
here on Windows.
- Stop #including `process.h` into files where it was not necessary.
This is everywhere, except `lib/curl_threads.c`.
> Strangely enough, `lib/curl_threads.c` compiled fine with autotools
> because `process.h` is also indirecty included via `unistd.h`. This
> might have been broken in autotools MSVC builds, where the latter
> header is missing.
- Delete all remaining `HAVE_PROCESS_H` feature guards, for they were
unnecessary.
- Delete `HAVE_PROCESS_H` detection from CMake and predefined values
from `lib/config-*.h` headers.
Reviewed-by: Jay Satiro
Closes#9703
b563a92cd6