include/host-build.mk: set Host/Exports for Host/Install step

Having a different PATH in Host/Install than in other steps like Host/Build
is confusing and easily leads to mistakes. Setting all of Host/Exports
makes host builds match target builds (Build/Install is part of
$(STAMP_BUILT), which has Build/Exports set).

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

include/host-build.mk

@@ -172,6 +172,7 @@ ifndef DUMP
 		$(foreach hook,$(Hooks/HostCompile/Post),$(call $(hook))$(sep))
 		touch $$@
 
+  $(call Host/Exports,$(HOST_STAMP_INSTALLED))
   $(HOST_STAMP_INSTALLED): $(HOST_STAMP_BUILT) $(if $(FORCE_HOST_INSTALL),FORCE)
 		$(call Host/Install,$(HOST_BUILD_PREFIX))
 		$(foreach hook,$(Hooks/HostInstall/Post),$(call $(hook))$(sep))