With submodules and equivalence declarations, name mangling may result in
long internal symbols overflowing internal buffers.  We now check that
we do not exceed the enlarged buffer sizes.

gcc/fortran/
	PR fortran/95707
	* gfortran.h (gfc_common_head): Enlarge buffer.
	* trans-common.c (gfc_sym_mangled_common_id): Enlarge temporary
	buffers, and add check on length on mangled name to prevent
	overflow.

(cherry picked from commit 3345e74299687de6144b87c0632018cafd4ccf3b)