Add a method to cancel interruption requests in liblwgeom

git-svn-id: http://svn.osgeo.org/postgis/trunk@13101 b70326c6-7e19-0410-871a-916f4a2858ee
Ignore another generated file

git-svn-id: http://svn.osgeo.org/postgis/trunk@13102 b70326c6-7e19-0410-871a-916f4a2858ee