MIPS/LD: Correct `mips-*-windiss' target emulation configuration

MIPS/LD: Correct `mips-*-windiss' target emulation configuration

Fix an issue with commit 73934d319dae ("Disable .gnu.hash on MIPS
targets"), <https://sourceware.org/ml/binutils/2006-07/msg00341.html>,
which in turn caused a regression with commit 861fb55ab50a ("Defer
allocation of R_MIPS_REL32 GOT slots"),
<https://sourceware.org/ml/binutils/2008-08/msg00096.html>, and use
`mipself.em' as the extra emulation file for `mips-*-windiss' targets,
removing a segmentation fault triggered as `_bfd_mips_elf_final_link'
calls `htab_traverse' to process LA25 stubs with `htab->la25_stubs'
being NULL.  This is in turn due to `_bfd_mips_elf_init_stubs' not
having been called, which is only done by `mipself.em'.  No LA25 stubs
are supposed to be produced for `mips-*-windiss' targets, however the
internal data structures have to be initialized.

	ld/
	* emulparams/elf32mipswindiss.sh (EXTRA_EM_FILE): Set to
	`mipself'.