Building gmp and mpfr within gcc

[NightStrike]

If I place gmp and mpfr within the gcc directory structure and build
gcc without using the --with-gmp/mpfr options, gcc compiles (I
believe) static versions of gmp and mpfr.  How can I find out what all
the options are that gcc uses to build those two things?  There are a
number of options available to configure for both gmp and mpfr, and I
am curious how gcc is compiling them.