Add support for disabling offline raster storage at compile time

Adds --disable-offline-raster configure switch
Testsuite fails with offline rasters disabled (could be fixed to
skip offline raster tests)

git-svn-id: http://svn.osgeo.org/postgis/trunk@12450 b70326c6-7e19-0410-871a-916f4a2858ee
Fix build with offline raster enabled (the default)

git-svn-id: http://svn.osgeo.org/postgis/trunk@12451 b70326c6-7e19-0410-871a-916f4a2858ee
Allow specifying name of regress database on make check

Honours a POSTGIS_REGRESS_DB environment variable

git-svn-id: http://svn.osgeo.org/postgis/trunk@12452 b70326c6-7e19-0410-871a-916f4a2858ee