Did you run ldconfig (as root) after the install?
Nope! I didn't! Should I have done it?
Yes. Someone has to tell the system where to find the library! ldconfig searches all directories specified in /etc/ld.so.conf and adds new libraries to its cache, which is then referred to. The -v option additionally outputs the cache to stdout. See the fine manual page.
First I thought this is a glaring bug in autoconf/make install, it should determine if ldconfig exists and start it after install. But think twice: would you want to run ldconfig every time you install a package in an automatic 1000 package compile/installation?
What's the output of ldconfig -v | grep gc ?
libgcc_s.so.1 -> libgcc_s-3.4.2-20041018.so.1 libgcj.so.5 -> libgcj.so.5.0.0 libgconf-1.so.1 -> libgconf-1.so.1.0.4 libgstgconf-0.8.so.0 -> libgstgconf-0.8.so.0.1.0 libgconf-2.so.4 -> libgconf-2.so.4.1.0 libgconf-gtk-1.so.1 -> libgconf-gtk-1.so.1.0.0 libgcrypt.so.11 -> libgcrypt.so.11.1.1
See? Your libgc is missing, I get here
libgcc_s.so.1 -> libgcc_s.so.1 libgc.so.1 -> libgc.so.1.0.2 <----------- libgccpp.so.1 -> libgccpp.so.1.0.2 libsigc-2.0.so.0 -> libsigc-2.0.so.0.0.0 libgcc_s.so.1 -> libgcc_s.so.1
ralf