tests: Relax receive_SUITE time constraint
tests: Refactor away ?line macro
tests: Relax system_profile_SUITE scheduler test
snmp: Silence debug in tests
os_mon: Relax disksup_SUITE api test
os_mon: Refactor disksup_SUITE

Notably, remove ?line macro.
os_mon: Fix freebsd diskspace queries

Use 'df -k -l' to query FreeBSD about diskspace on local disks.
Previously 'df' -k -t ufs' was used but this will not handle zfs
disks. Just use '-l' instead of listing potential filesystems.
os_mon: Fix openbsd diskspace queries

Use 'df -k -l' to query OpenBSD about diskspace on local disks.
Same reasoning as for FreeBSD - additional filesystems without
listing them all.
os_mon: Relax disksup_SUITE test even more

Capacity can be zero on certain filesystems.
Remove reported mountpoints with zero capacity during tests since
these reports false positives.
Fix changing terminal parameters in to_erl

One of our devices does not like 'to_erl' to be run over a serial port.
When to_erl is started, we see "Attaching to /tm<0xFF>" being printed
and the device then refuses to accept any input. Occasionally, we have
seen a linux kernel error message "serial8250: too much work for irq16"
simultaneously. After some debugging we found out that cause is a call
to tcsetattr() by to_erl, immediately preceeded by some printf().

The UART in our device doesn't like hardware parameters to be changed
while output is concurrently active. In fact, the GNU libc manual also
mentions that it might be dangerous to change UART hardware parameters
when a transmission is ongoing.

The patch attached to this e-mail changes the behaviour of to_erl to use
TCSADRAIN instead of TCSANOW when changing terminal parameters. This
makes the serial driver wait for the output queues to be empty before
applying the terminal parameter change.
Merge branch 'sze/to_erl/OTP-11206' into maint

* sze/to_erl/OTP-11206:
  Fix changing terminal parameters in to_erl
Merge branch 'egil/test-cuddling' into maint
Merge branch 'egil/os_mon/fix-bsd-disksup/OTP-11207' into maint

* egil/os_mon/fix-bsd-disksup/OTP-11207:
  os_mon: Fix openbsd diskspace queries
  os_mon: Fix freebsd diskspace queries