ZTS: Another round of changes for FreeBSD

Highlights:
* is_linux -> is_illumos swaps
* make block_device_wait more clever when paths are given
* slightly optimize default_cleanup_noexit
* remove platform differences in user_run
* temporarily expect non-libfetch behavior for keylocation=/foo/bar
* fix sharenfs exceptions
* don't test multihost property
* fix misc broken platform checks
* clear zinjected faults in removal_resume_export callback

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10092

tests/zfs-tests/include/blkdev.shlib

@@ -74,14 +74,33 @@ function block_device_wait
 {
 	if is_linux; then
 		udevadm trigger $*
-		typeset local start=$SECONDS
+		typeset start=$SECONDS
 		udevadm settle
-		typeset local elapsed=$((SECONDS - start))
+		typeset elapsed=$((SECONDS - start))
 		[[ $elapsed > 60 ]] && \
 		    log_note udevadm settle time too long: $elapsed
 	elif is_freebsd; then
-		sleep 3
+		if [[ ${#@} -eq 0 ]]; then
+			sleep 3
+			return
+		fi
 	fi
+	# Poll for the given paths to appear, but give up eventually.
+	typeset -i i
+	for (( i = 0; i < 5; ++i )); do
+		typeset missing=false
+		typeset dev
+		for dev in "${@}"; do
+			if ! [[ -f $dev ]]; then
+				missing=true
+				break
+			fi
+		done
+		if ! $missing; then
+			break
+		fi
+		sleep ${#@}
+	done
 }
 
 #