If configure phase failes with this message, then most likely the dev-libs/mpc package is removed. I removed it accidentally. Afterwards I was unable to
emerge anything. Here is a simple solution for the issue.
Download stage3 tar ball from a Gentoo mirror, unpack it and copy
/usr/lib. Then run
ldconfig and try to build something.
Hopefully, the post will help another gentoer like me who will also wonder what's going wrong with the C compiler.