ZTS: Misc fixes for FreeBSD

* Set geom debug flags in corrupt_blocks_at_level
* Use the right time zone for history tests
* Add missing commands.cfg entry for diskinfo
* Rewrite get_last_txg_synced to use zdb
* Don't check ulimits for sparse files
* Suspend removal before removing a vdev, not after

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10054

tests/zfs-tests/include/blkdev.shlib

@@ -577,6 +577,11 @@ function corrupt_blocks_at_level # input_file corrupt_level
 
 	[[ -f $input_file ]] || log_fail "Couldn't find $input_file"
 
+	if is_freebsd; then
+		# Temporarily allow corrupting an inuse device.
+		debugflags=$(sysctl -n kern.geom.debugflags)
+		sysctl kern.geom.debugflags=16
+	fi
 
 	log_must list_file_blocks $input_file | \
 	    while read level path offset length; do
@@ -586,6 +591,10 @@ function corrupt_blocks_at_level # input_file corrupt_level
 		fi
 	    done
 
+	if is_freebsd; then
+		sysctl kern.geom.debugflags=$debugflags
+	fi
+
 	# This is necessary for pools made of loop devices.
 	sync
 }

tests/zfs-tests/include/commands.cfg

@@ -113,6 +113,7 @@ export SYSTEM_FILES_COMMON='arp
 
 export SYSTEM_FILES_FREEBSD='chflags
     compress
+    diskinfo
     dumpon
     env
     fsck