runtime: revert eqtype for AIX

AIX linker is not able to merge identical type descriptors in a single
symbol if there are coming from different object or shared object files.
This results into several pointers referencing the same type
descriptors.
Thus, eqtype is needed to ensure that these different symbols will be
considered as the same type descriptor.

Fixes golang/go#39276

gcc/go/ChangeLog:

	* go-c.h (struct go_create_gogo_args): Add need_eqtype field.
	* go-lang.c (go_langhook_init): Set need_eqtype.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/235697