xbps-src: added XBPS_LDFLAGS into xbps-src.conf

[Juan RP]

Hi,

I've just added a new variable to the xbps-src configuration file
to pass custom LDFLAGS settings when building packages.

By default it uses "--as-needed" that avoids linking extra libraries into
the binaries, only symbols from direct dependencies are linked in.

Here's the commit log and its code:

http://groups.google.com/group/xbps-commits/browse_thread/thread/2cc1fa70ba222432

Cheers!