Dear all,

I've committed the attached, simple & obvious patch for a
gmp memory leak in gfc_get_nodesc_array_type that shows
up when running f951 under valgrind e.g. on testcase
gfortran.dg/class_optional_2.f90, after regtesting on
x86_64-pc-linux-gnu.

(Note that this does not address the underlying issues
of pr55978).

Thanks,
Harald