There is a __used member in glibc's posix_spawn_file_actions_t in
spawn.h, so we must temporarily undefine __used when including it,
otherwise Support/Unix/Program.inc fails to build. This is based on
similar handling for __unused in other headers.
Fixes: 31ba4ce889 ("Allow bootstrapping llvm-tblgen on macOS and Linux")
MFC after: 1 week
This is needed to bootstrap llvm-tblgen on Linux since LLVM calls
`::open(...)` which does not work if open is a statement macro.
Also stop defining O_SHLOCK/O_EXLOCK and update the only bootstrap tools
user of those flags to deal with missing definitions.
Reviewed By: jrtc27
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D31226
Older glibc headers did some very nasty things that have since been
sanitised. We could also fix this by adding a linux/getopt.h wrapper
alongside the existing common/getopt.h that #undef's __need_getopt, but
that seems a little more hacky and complicated.
Reviewed by: arichardson
These headers are required in order to build the bootstrap tools on macOS
and Linux. A follow-up commit will add implementations of functions that
don't exist on those operating systems to -legacy when bootstrapping.
Reviewed By: brooks
Differential Revision: https://reviews.freebsd.org/D14316
