Only link to required libraries

[artem]

At the moment libmapnik is linked to libpq, sqlite3 etc. We should only link to required libraries.

[springmeyer]

Nice catch. I see this too. Likely a by-product of my SCons plugin mucking pre 0.6.0.

I bet the right approach here is to have a Scons environment for each plugin, so that when adding libs needed for plugins only they don't pollute the Scons env used to build libmapnik.dylib. It looks like libpq and libsqlite are currently are being removed but since plugins are built after libmapnik.dylib this is ineffective.

I'll try to find time to look into this more later in the week.

[springmeyer]

note: #214 lists needed thinking on Scons use that should make easier/prevent issues like this.

[springmeyer]

right approach here is to selectively limit which libs are linked in source:src/SConscript.

r1197 does this, tested on osx and ubuntu.

[springmeyer]

with r1198 cairo checking is more robust. Closing as this now works on freebsd as well.