* configure.ac: Change required MPFR from 2.2.0 -> 2.2.1.
	Change recommended MPFR from 2.2.1 > 2.3.0.
	* configure: Regenerate.

gcc:
	* doc/install.texi: Change recommended MPFR from 2.2.1 > 2.3.0.

testsuite:
	* gcc.dg/torture/builtin-math-4.c: Remove XFAIL.

From-SVN: r131018