Instead of maintaining lists per compiler of flags that should
be enabled / disabled we now test for them instead. If they are
able to be used we append them.
Same with linker flags we test for them before assuming they work.
When building on Ubuntu (14.04 with cmake 3.2.2) the -fPIC flag needs to be added when compiling. This change fixes that issue, but I don't know how it will affect building on other systems.
Plex-CLA-1.0-signed-off-by: Niclas Berglind <nb@kjam.se>