Ubuntu CI doesn't use compiled version of downloaded SQLite source code

[mkgrgis]

FDW testing uses system SQLite library, not specially compiled.

Some details #109

[mkgrgis]

This problem was resolved in install_sqlite.sh:

• install SQLite with -prefix= for PostgreSQL temporary installation like /usr/local/pgsql
• install SQLite before PostGIS, because GDAL dependency of PostGIS uses SQLite with column metadata
• export CFLAGS=-DSQLITE_ENABLE_COLUMN_METADATA for SQlite because required by GDAL->raster->PostGIS

Resolved in #109

[mkgrgis]

Closed by merging results of #114.