gdal: Avoid host headers use for SQlite3

This fixes the host contamination when the host has the SQLite3
headers available.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
libxml++: Upgrade to 2.37.1 and add ptest support

Signed-off-by: Nick Lewis <nick.lewis@usa.g4s.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>