Allow pesize change to adjust free values

Hi folks

I run again over the problem that vgchange is able to change the size of a PE, but refuses to recalculate certain free values.

The attached patch seems to work for one PV but it it is not safe for more. It may change the following things:
- Number of extents in VG.
- Free space of VG.
- Number of extents in PV.
- Size of free PV segment.

Fix for the later: Do PV resize as in this patch. Collect numbers of removed extents and remove them from the VG.

@@ -405,14 +405,6 @@
 		return EINVALID_CMD_LINE;
 	}
 
-	if (extent_size > vg->extent_size) {
-		if ((uint64_t) vg->extent_size * vg->extent_count % extent_size) {
-			/* FIXME Adjust used PV sizes instead */
-			log_error("New extent size is not a perfect fit");
-			return EINVALID_CMD_LINE;
-		}
-	}
-
 	if (!archive(vg))
 		return ECMD_FAILED;
 

Each kiss is as the first.
		-- Miramanee, Kirk's wife, "The Paradise Syndrome",
		   stardate 4842.6