cache: Properly rename origin LV tree when adding "_corig"

When creating a cache LV with a RAID origin, we need to ensure that
the sub-LVs of that origin properly change their names to include
the "_corig" extention of the top-level LV.  We do this by first
performing a 'lv_rename_update' before making the call to
'insert_layer_for_lv'.
poll_daemon:  Cleanly exit polling if the LV is no longer active

If the we are polling an LV due to some sort of conversion and it
becomes inactive, a rather worrisome message is produced, e.g.:
"  ABORTING: Mirror percentage check failed."

We can cleanly exit if we do a simple check to see if the LV is
active before performing the check.  This eliminates the scary
message.
snapshot: check it's still snapshot

While polling for snapshot, detect first the snapshot still
exits.  It's valid to have multiple polling threads watching
for the same thing and just 1 can 'win' the finish part.
All others should nicely 'fail'.
snapshot: check snapshot exists

Return 0 if the LV is not even snapshot.
snapshot: do not spawn when origin is not active

Since the code is not doing anything when origin is not active,
avoid spawning polling thread.
snapshot: report proper error message

Expresing -lXX%LV is not valid for snapshot, but error message for
snapshost case was not complete and missed %ORIGIN.
Also document correct settings for in manpage properly where
it missed %PVS.
snapshot: %ORIGIN is relative to data size

Let's use the size of origin as the real base for percenta calculation,
and 'silenly' add needed metadata space for snapshot.

So now command   'lvcreate -s -l100%ORIGIN vg/lv' should always create a
snapshot to handle full device overwrite.
cleanup: use stack for small buffer

Avoid error checking of allocation error when just few bytes are needed
for short string and use stack.
Stacktrace lvmetad_pv_gone() fail path.
cleanup: we already know max device name size

Use NAME_LEN constant to simplify creation of device name.
Since the max size should be already tested in validation,
throw INTERNAL_ERROR if the size of vg/lv is bigger then NAME_LEN.
tests: wait for udev

Before test exits, wait for udev.
tests: detect version of thin_restore command

Skip test when missing.
tests: check new snapshot skills
report: select: add DM_REPORT_FIELD_TYPE_SIZE to make a difference between NUMBER and SIZE

This makes it easier to check against the fields (following patches for
report selection) and check whether size units are allowed or not
with the field value.
report: select: add structs for report selection

This is rebased and edited version of the original design and
patch proposed by Jun'ichi Nomura:
  http://www.redhat.com/archives/dm-devel/2007-April/msg00025.html

This patch defines operators and structures that will be used
to store the report selection against which the actual values
reported will be checked.

  Selection operators
  -------------------
    Comparison operators:
        =~  - Matching regular expression.
        !~  - Not matching regular expression.
         =  - Equal to.
        !=  - Not equal to.
        >=  - Greater than or equal to.
         >  - Greater than
        <=  - Less than or equal to.
         <  - Less than.

    Logical and grouping operators:
        &&  - All fields must match
         ,  - All fields must match
        ||  - At least one field must match
         #  - At least one field must match
         !  - Logical negation
         (  - Left parenthesis
         )  - Right parenthesis
report: select: add supporting infrastucture for token parsing in report selections

This is rebased and edited version of the original design and
patch proposed by Jun'ichi Nomura:
  http://www.redhat.com/archives/dm-devel/2007-April/msg00025.html

Add support for parsing numbers, strings (quoted or unquoted), regexes
and operators amogst these operands in selection condition supplied.
report: select: add dm_report_init_with_selection to libdm

This is rebased and edited version of the original design and
patch proposed by Jun'ichi Nomura:
  http://www.redhat.com/archives/dm-devel/2007-April/msg00025.html

The dm_report_init_with_selection is the same as dm_report_init
but it contains an additional argument to set the selection
in the form of a string that contains field names to check against and
selection operators. The selection string is parsend and a selection
tree is composed for use in the checks against individual fields when
the report is processed. The parsed selection tree is stored in dm_report
structure as "selection_root".
report: select: add _check_selection fn to support checking fields against given selections

This is rebased and edited versions of the original design and
patch proposed by Jun'ichi Nomura:
  http://www.redhat.com/archives/dm-devel/2007-April/msg00025.html

The _check_selection implements the actual field checking against the
selection tree.
report: select: use _check_report_selection in dm_report_object to report only objects that satisfy the report selection

This is rebased and edited version of the original design and
patch proposed by Jun'ichi Nomura:
  http://www.redhat.com/archives/dm-devel/2007-April/msg00025.html

This activates the actual selection process in dm_report_object.
report: select: add --select arg to dmsetup
report: select: add --select arg to pvs, vgs and lvs