Fix LVM2 PV shrinking with lvm2 2.02.171 and later (#1)

Shrinking an LVM2 Physical Volume on CentOS 7 with the latest
lvm2 2.02.177 fails like this:

  Shrink /dev/sda9 from 1.00 GiB to 768.00 MiB
  * calibrate /dev/sda9
  * check file system on /dev/sda9 for errors and (if possib...(SUCCESS)
  * shrink file system                                         (ERROR)
    * lvm pvresize -v --setphysicalvolumesize 786432K '/dev/...(ERROR)
        0 physical volume(s) resized / 1 physical volume(s) not resized

        Wiping internal VG cache
        Wiping cache of LVM-capable devices
        /dev/sda9: Requested size 712.00 MiB is less than real size 1.00 GiB.  Proceed? [y/n]:[n]
        Physical Volume /dev/sda9 not resized.

This upstream change to lvm2 [1] makes pvresize prompt for confirmation
whenever the --setphysicalvolumesize option is used.  (The change was
included in lvm2 2.02.171 and later, which is used in recent
distributions.  The reporter found the issue on Ubuntu 18.04 LTS and I
reproduced the issue on RHEL/CentOS 7.5).  The set size option has to be
used when shrinking the PV before shrinking the partition therefore fix
this issue by adding lvm common option --yes when using the set size
option.

[1] https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=cbc69f8c693edf0d1307c9447e2e66d07a04bfe9
    pvresize: Prompt when non-default size supplied.

Closes #1 - Can't shrink LVM partition due to pvresize prompt

src/lvm2_pv.cc

@@ -103,7 +103,7 @@ bool lvm2_pv::resize( const Partition & partition_new, OperationDetail & operati
 {
 	Glib::ustring size = "" ;
 	if ( ! fill_partition )
-		size = " --setphysicalvolumesize " +
+		size = " --yes --setphysicalvolumesize " +
 			Utils::num_to_str( floor( Utils::sector_to_unit(
 				partition_new .get_sector_length(), partition_new .sector_size, UNIT_KIB ) ) ) + "K " ;
 	return ! execute_command( "lvm pvresize -v " + size + Glib::shell_quote( partition_new.get_path() ),