stubdom: remove support for grub-pv

The Mini-OS based grub-pv is not being built by default since Xen 4.16.
Additionally it can be replaced in most cases by the more modern pvgrub
(part of grub upstream), while grub-pv is based on legacy grub 0.97.

In case someone is really depending on grub-pv, an old build from a
previous Xen version can be used without any problem, as only stable
hypercall interfaces are used by it.

Remove grub-pv from the build system.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Acked-by: Jan Beulich <jbeulich@suse.com>

Makefile

@@ -71,9 +71,6 @@ build-tools-oxenstored: build-tools-public-headers
 .PHONY: build-stubdom
 build-stubdom: mini-os-dir build-tools-public-headers
 	$(MAKE) -C stubdom build
-ifeq (x86_64,$(XEN_TARGET_ARCH))
-	XEN_TARGET_ARCH=x86_32 $(MAKE) -C stubdom pv-grub-if-enabled
-endif
 
 define do-subtree
 $(1)/%: FORCE
@@ -149,9 +146,6 @@ install-tools: install-tools-public-headers
 .PHONY: install-stubdom
 install-stubdom: mini-os-dir install-tools-public-headers
 	$(MAKE) -C stubdom install
-ifeq (x86_64,$(XEN_TARGET_ARCH))
-	XEN_TARGET_ARCH=x86_32 $(MAKE) -C stubdom install-grub-if-enabled
-endif
 
 .PHONY: tools/firmware/seabios-dir-force-update
 tools/firmware/seabios-dir-force-update: