[Bug fortran/46540] libquadmath: Implement --disable-libquadmath

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46540

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2010-11-18 
13:13:11 UTC ---
Probably also needs some update of the general GCC documentation such as
"install".