Bug#807558: postgis: liblwgeom 2.2.0 breaks spatialite

[Bas Couwenberg]

Source: postgis
Version: 2.2.0+dfsg-1
Severity: serious
Tags: upstream
Justification: Breaks spatialite

lw_vasprintf was removed in liblwgeom 2.2.0, but it's required for
SpatiaLite 4.3.0a.

This RC bug is needed to prevent testing migration.