Today I tried installing Ruby 2.2.0, which just came out, on my Ubuntu 14.04 (Trusty) machine.
The build (through the excellent ruby-build) failed though, and inspecting the logs, the error seemed to be related to
linking shared-object fiddle.so /usr/bin/ld: ./libffi-3.2.1/.libs/libffi.a(raw_api.o): relocation R_X86_64_32S against `.rodata' can not be used when making a shared object; recompile with -fPIC ./libffi-3.2.1/.libs/libffi.a: error adding symbols: Bad value collect2: error: ld returned 1 exit status
The solution was to simply install
sudo aptitude install libffi-dev
And then the installation proceeded without problems.