build to tail_build with partial build in tail_build

- instead on lots of recursive build.pl modules to iterate through we build all
  tail_build up to the requested module inside one tail_build when doing a
  "make foo.all"
- advantage: speeding up because getting rid of lots of recursive makes with
  artificial module barriers, forcing almost sequential execution: build, link,
  unittest with lots of cpu-idling at each module-end
- disadvantage: all shared dependencies of tail_build are now build for a
  (sub)module of tail_build. This is transitional as we migrate more stuff into
  tail_build and there are good dependencies inside tail_build
- "make foo.all" now only executes slowcheck now for foo, not for all the deps

Makefile

@@ -241,15 +241,23 @@ xpdf\
 xsltml\
 zlib\
 
+gb_TAILBUILDMODULES := $(shell make -f $(SRCDIR)/tail_build/Makefile showmodules)
+
 define gbuild_module_rules
 .PHONY: $(1) $(1).all $(1).clean $(1).deliver
 
 $(1): bootstrap fetch
 	cd $(1) && $(GNUMAKE) -j $(GMAKE_PARALLELISM) $(GMAKE_OPTIONS) gb_PARTIALBUILD=T
 
+ifeq ($(filter $(1),$(gb_TAILBUILDMODULES)),)
 $(1).all: bootstrap fetch
 	cd $(1) && unset MAKEFLAGS && \
         $(SOLARENV)/bin/build.pl -P$(BUILD_NCPUS) --all -- -P$(GMAKE_PARALLELISM)
+else 
+$(1).all: bootstrap fetch
+	cd tail_build && unset MAKEFLAGS && export gb_TAILBUILDTARGET="$(WORKDIR)/Module/$(1) $(WORKDIR)/Module/check/$(1)" && \
+        $(SOLARENV)/bin/build.pl -P$(BUILD_NCPUS) --all -- -P$(GMAKE_PARALLELISM)
+endif
 
 $(1).clean:
 	cd $(1) && $(GNUMAKE) -j $(GMAKE_PARALLELISM) $(GMAKE_OPTIONS) clean gb_PARTIALBUILD=T

solenv/inc/gbuildbridge.mk

@@ -30,12 +30,16 @@ TARGET=prj
 
 .INCLUDE : settings.mk
 
+.IF "$(GBUILDTARGET)" == ""
+GBUILDTARGET=all slowcheck
+.END
+
 .IF "$(depend)" != ""
 all:
 .ELIF "$(VERBOSE)"!=""
 all:
-	cd $(PRJ) && $(GNUMAKE) -r -j$(GMAKE_MODULE_PARALLELISM) all slowcheck
+	cd $(PRJ) && $(GNUMAKE) -r -j$(GMAKE_MODULE_PARALLELISM) $(GBUILDTARGET)
 .ELSE
 all:
-	@cd $(PRJ) && $(GNUMAKE) -rs -j$(GMAKE_MODULE_PARALLELISM) all slowcheck
+	@cd $(PRJ) && $(GNUMAKE) -rs -j$(GMAKE_MODULE_PARALLELISM) $(GBUILDTARGET)
 .END

tail_build/prj/makefile.mk

 GMAKE_MODULE_PARALLELISM := $(GMAKE_PARALLELISM) # tail_build is special!
+.IF "$(gb_TAILBUILDTARGET)" != ""
+GBUILDTARGET=$(gb_TAILBUILDTARGET)
+.END
 .INCLUDE : gbuildbridge.mk