Ah yes, you've triggered a latent memory. Try moving/renaming the libgcc_s.so.1 to libgcc_s.so.1.orig in the <QUARTUS_ROOTDIR>/linux directory. That's what I had to do nearly 6 months ago to get it to work on my flavors of Linux. The Quartus executables that link to this library are now linking to the libraries installed as part of GCC on my systems.
It also might work, for you, if you can alter the shell script which wraps Quartus to fool it into believing you're running RH7.3. There's another libgcc_s.so.1 library in <QUARTUS_ROOTDIR>/adm/syslibs/rh7.3.
Mind you, I don't use the GUI for most tasks anyway.... which is a good thing since it's hardly functional on Linux.
Hope this works for you! YMMV disclaimers apply...
Cheers,
- slacker