depends: set env-provided flags to per-release

Users can now safely set flags and have them override the optional
per-release-type flags.

This also means that user-provided flags will now be forwarded to CMake's
build-type flags variables so that they'll correctly override the existing
values.

depends/hosts/default.mk

@@ -28,12 +28,11 @@ endef
 
 define add_host_flags_func
 ifeq ($(filter $(origin $1),undefined default),)
-$(host_arch)_$(host_os)_$1 = $($1)
-$(host_arch)_$(host_os)_$(release_type)_$1 =
+$(host_arch)_$(host_os)_$(release_type)_$1 = $($1)
 else
-$(host_arch)_$(host_os)_$1 += $($(host_os)_$1)
 $(host_arch)_$(host_os)_$(release_type)_$1 += $($(host_os)_$(release_type)_$1)
 endif
+$(host_arch)_$(host_os)_$1 += $($(host_os)_$1)
 host_$1 = $$($(host_arch)_$(host_os)_$1)
 host_$(release_type)_$1 = $$($(host_arch)_$(host_os)_$(release_type)_$1)
 endef