* follow-symlinks: allows mergerfs to transparently follow symlinks
* link-exdev: in the event a link returns EXDEV create a symlink instead
* rename-exdev: in the event a rename returns EXDEV move the oldpath and
create a symlink for the newpath
Add INTERNAL_FUSE variable to control linking against
bundled libfuse vs external/system libfuse.
If external libfuse is requested,
`pkg-config` is used to obtain CFLAGS/LIBS/LDFLAGS and
to check that the provided external libfuse is >= 2.9.7.
This might hopefully get mergerfs closer to inclusion into distros.
Link: https://github.com/trapexit/mergerfs/issues/431
Link: https://bugs.gentoo.org/587956#c6
These are more like LIBS rather than LDFLAGS.
They are used just in one place,
so simply put them inline.
Also, use LDFLAGS provided by the user during actual link.
This helps users pass their own LDFLAGS.
For example, this is important on Gentoo,
where LDFLAGS='-Wl,-O1 -Wl,--as-needed' is passed by default.
This feature mimics the standard mhddfs behavior but is more thorough.
If a write fails and the errno is set to ENOSPC then mergerfs will (if
the feature is enabled) attempt to move the file to the drive with
the most free space but only if it has enough room for the file plus
the amount to be written. If that transfer is successful it will then
unlink the original file and attempt the previously failed write again.
The copy includes copying the path and file including the acls, owners,
attributes, extended attributes, and timestamps.