Fix DBus issues: popcornmix/omxplayer#59 and popcornmix/omxplayer#97
Uses an adapted version of fcarlier fix.
Fix an issue with LD_LIBRARY_PATH. If LD_LIBRARY_PATH is empty it
includes the current directory due the calculated variable ends
with ":". Avoid that not adding LD_LIBRARY_PATH if not set.

Issue discovered by popcornmix who sent me this link:
http://stick.gk2.sk/2009/10/wrong-usage-of-ld_library_path/