gbuild: fix generated deps for API headers

This should be reverted after some time, as it solves a one-time
problem.

Change-Id: Iaa4bc17267a24bd744573e56108b8d207936629c
Reviewed-on: https://gerrit.libreoffice.org/3506Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>

solenv/gbuild/UnoApi.mk

@@ -7,6 +7,15 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 #
 
+# NOTE: This is needed temporarily to force rebuild with API files from
+# $(WORKDIR), thus fixing generated deps. Otherwise, a change of an .idl
+# file would not rebuild a .cxx if it still depended on the $(OUTDIR)
+# version of the header.
+define gb_UnoApi__make_outdir_headers_rule
+$(OUTDIR)/inc/$(1)/%.hdl $(OUTDIR)/inc/$(1)/%.hpp :
+	@true
+endef
+
 .PHONY : $(call gb_UnoApi_get_clean_target,%)
 $(call gb_UnoApi_get_clean_target,%) :
 	$(call gb_Helper_abbreviate_dirs,\
@@ -28,6 +37,8 @@ $(call gb_UnoApi_get_clean_target,$(1)) : $(call gb_UnoApiHeadersTarget_get_clea
 
 $(call gb_UnoApiTarget_get_headers_target,$(1)) : $(call gb_Package_get_target,$(1)_idl)
 
+$(call gb_UnoApi__make_outdir_headers_rule,$(1))
+
 $(call gb_Deliver_add_deliverable,$(call gb_UnoApi_get_target,$(1)),$(call gb_UnoApiTarget_get_target,$(1)),$(1))
 
 $$(eval $$(call gb_Module_register_target,$(call gb_UnoApi_get_target,$(1)),$(call gb_UnoApi_get_clean_target,$(1))))