[Bug modula2/105391] gm2 doesn't heed --with-gmp*

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105391

--- Comment #1 from Rainer Orth <ro at gcc dot gnu.org> ---
Created attachment 52883
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52883&action=edit
Hacky patch