MFC r253076: rc.d/zfs: pass -v option to zfs mount
MFC r253067: zfsboottest: sync with changes in zfs boot code
MFC r253068: zfsboottest.sh: remove checks for things that are not
strictly required
MFC r253605: zfsboottest: remove explicit -Werror
MFC r253072: amd64: use -mno-omit-leaf-frame-pointer in addition to
-fno-omit-frame-pointer
MFC r253601: newvers.sh: fix the fallback case of git-svn detection
MFC r253602: newvers.sh: add another git-svn fallback
MFC r253070: zfs: load zpool.cache after a root fs is mounted
MFC r253073: zfs: try to properly handle i/o errors in mappedread_sf