don't try to sign merged libs on windows

as those are fake, just textfiles with dll extension that signtool
doesn't like.
Also made the text more descriptive "invalid" is ambiguous,
"invalid - merged lib" states the reason why the file is a dummy.

Change-Id: I31801fd0c3aa593549fac5e6275189e18bbc0010
Reviewed-on: https://gerrit.libreoffice.org/15444Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

postprocess/CustomTarget_signing.mk

@@ -29,8 +29,11 @@ $(call gb_CustomTarget_get_workdir,postprocess/signing)/signing.done:
 	$(call gb_Output_announce,$(subst $(WORKDIR)/,,$@),$(true),PRL,2)
 ifeq ($(COM),MSC)
 ifneq ($(ENABLE_DBGUTIL),TRUE)
+	EXCLUDELIST=$(shell $(gb_MKTEMP)) && \
+	cat $(SRCDIR)/postprocess/signing/no_signing.txt > $$EXCLUDELIST && \
+	echo "$(foreach lib,$(gb_MERGEDLIBS),$(call gb_Library_get_filename,$(lib)))" | tr ' ' '\n' >> $$EXCLUDELIST && \
 	$(PERL) $(SRCDIR)/postprocess/signing/signing.pl \
-			-e $(SRCDIR)/postprocess/signing/no_signing.txt \
+			-e $$EXCLUDELIST \
 			-l $(subst .done,_log.txt,$@) \
 			$(if $(PFXFILE),-f $(PFXFILE)) \
 			$(if $(PFXPASSWORD),-p $(PFXPASSWORD)) \
@@ -43,7 +46,7 @@ ifneq ($(ENABLE_DBGUTIL),TRUE)
 			$(INSTDIR)/sdk/cli/*.dll \
 			$(INSTDIR)/sdk/bin/*.exe \
 			$(INSTDIR)/share/extensions/mysql-connector-ooo/*.dll\
-	&& touch $@
+	&& rm $$EXCLUDELIST && touch $@
 else
 	@echo "Doing nothing on non product builds ..."
 endif

solenv/gbuild/LinkTarget.mk

@@ -486,8 +486,8 @@ define gb_LinkTarget__command_impl
 	$(if $(filter $(2),$(foreach lib,$(gb_MERGEDLIBS),$(call gb_Library__get_workdir_linktargetname,$(lib)))),\
 		$(if $(filter $(true),$(call gb_LinkTarget__is_build_lib,$(2))),\
 			$(call gb_LinkTarget__command,$(1),$(2)),\
-			mkdir -p $(dir $(1)) && echo invalid > $(1) \
-			$(if $(SOVERSIONSCRIPT),&& echo invalid > $(WORKDIR)/LinkTarget/$(2))),\
+			mkdir -p $(dir $(1)) && echo invalid - merged lib > $(1) \
+			$(if $(SOVERSIONSCRIPT),&& echo invalid - merged lib > $(WORKDIR)/LinkTarget/$(2))),\
 		$(call gb_LinkTarget__command,$(1),$(2)))
 	$(call gb_LinkTarget__command_objectlist,$(WORKDIR)/LinkTarget/$(2).objectlist)
 endef