gbuild: incremental builds with --enable-pch are unsound

The problem is that the precompiled headers' dependency files are not
run through concat-deps, hence they directly refer to headers of
external libraries' headers, which are not targets in the build system;
therefore re-building an external library does not cause the dependent
PCH to re-build and (at least with MSVC) the object files don't depend
on headers included via PCH anyway, so we get the recent link failure
in comphelper with MSVC, which wasn't rebuilt for icu's ABI change.

To fix that just use concat-deps, which re-writes header dependencies to
UnpackedTarball target dependencies.

Change-Id: Ic7555822925aaa1ff09b29bb73801fb83923bfab
(cherry picked from commit 475cf23e)
Reviewed-on: https://gerrit.libreoffice.org/19550Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

solenv/gbuild/PrecompiledHeaders.mk

@@ -34,9 +34,18 @@ $(call gb_PrecompiledHeader_get_dep_target,%) :
 		mkdir -p $(dir $@) && \
 		echo "$(call gb_PrecompiledHeader_get_target,$*) : $(gb_Helper_PHONY)" > $@)
 
+# despite this being only one .d file, need to run concat-deps on it to
+# re-write external headers from UnpackedTarball
 $(call gb_PrecompiledHeader_get_target,%) :
 	rm -f $@
 	$(call gb_PrecompiledHeader__command,$@,$*,$<,$(PCH_DEFS),$(PCH_CXXFLAGS) $(gb_PrecompiledHeader_EXCEPTIONFLAGS),$(INCLUDE))
+ifeq ($(gb_FULLDEPS),$(true))
+	$(call gb_Helper_abbreviate_dirs,\
+		RESPONSEFILE=$(call var2file,$(shell $(gb_MKTEMP)),200,$(call gb_PrecompiledHeader_get_dep_target_tmp,$*)) && \
+		$(call gb_Executable_get_command,concat-deps) $${RESPONSEFILE} \
+			> $(call gb_PrecompiledHeader_get_dep_target,$*) && \
+		rm -f $${RESPONSEFILE} $(call gb_PrecompiledHeader_get_dep_target_tmp,$*))
+endif
 
 .PHONY : $(call gb_PrecompiledHeader_get_clean_target,%)
 $(call gb_PrecompiledHeader_get_clean_target,%) :

solenv/gbuild/TargetLocations.mk

@@ -131,6 +131,7 @@ gb_PackageSet_get_target = $(WORKDIR)/PackageSet/$(1).filelist
 gb_PackageInfo_get_target = $(WORKDIR)/PackageInfo
 gb_Postprocess_get_target = $(WORKDIR)/Postprocess/$(1)
 gb_PrecompiledHeader_get_dep_target = $(WORKDIR)/Dep/PrecompiledHeader/$(gb_PrecompiledHeader_DEBUGDIR)/$(1).hxx.gch.d
+gb_PrecompiledHeader_get_dep_target_tmp = $(call gb_PrecompiledHeader_get_dep_target,$(1)).tmp
 gb_PrecompiledHeader_get_target = $(WORKDIR)/PrecompiledHeader/$(gb_PrecompiledHeader_DEBUGDIR)/$(1).hxx.gch
 gb_PrecompiledHeader_get_timestamp = $(WORKDIR)/PrecompiledHeader/$(gb_PrecompiledHeader_DEBUGDIR)/Timestamps/$(1)
 gb_PropertiesTranslateTarget_get_target = $(WORKDIR)/PropertiesTranslateTarget/$(1).properties

solenv/gbuild/platform/com_GCC_class.mk

@@ -173,10 +173,10 @@ $(call gb_Helper_abbreviate_dirs,\
 		$(if $(VISIBILITY),,$(gb_VISIBILITY_FLAGS)) \
 		$(if $(EXTERNAL_CODE),$(gb_CXXFLAGS_Wundef),$(gb_DEFS_INTERNAL)) \
 		$(6) \
-		$(call gb_cxx_dep_generation_options,$(1),$(call gb_PrecompiledHeader_get_dep_target,$(2))) \
+		$(call gb_cxx_dep_generation_options,$(1),$(call gb_PrecompiledHeader_get_dep_target_tmp,$(2))) \
 		-c $(patsubst %.cxx,%.hxx,$(3)) \
 		-o$(1) \
-		$(call gb_cxx_dep_copy,$(call gb_PrecompiledHeader_get_dep_target,$(2))) \
+		$(call gb_cxx_dep_copy,$(call gb_PrecompiledHeader_get_dep_target_tmp,$(2))) \
 		)
 endef
 

solenv/gbuild/platform/com_MSC_class.mk

@@ -85,7 +85,7 @@ $(call gb_Helper_abbreviate_dirs,\
 		-I$(dir $(3)) \
 		$(6) \
 		-c $(3) \
-		-Yc$(notdir $(patsubst %.cxx,%.hxx,$(3))) -Fp$(1) -Fo$(1).obj) $(call gb_create_deps,$(call gb_PrecompiledHeader_get_dep_target,$(2)),$(1),$(3))
+		-Yc$(notdir $(patsubst %.cxx,%.hxx,$(3))) -Fp$(1) -Fo$(1).obj) $(call gb_create_deps,$(call gb_PrecompiledHeader_get_dep_target_tmp,$(2)),$(1),$(3))
 endef
 
 # AsmObject class