build: Introduce single container build target.

The intention is to batch all container invocations instead of
instanciating one for every rule that needs to run within a container.

This keeps track of build dependencies using a .any-build timestamp file
and define a CONTAINER=1 variable when make is running within the
container.

When running within the container, only "configure" and "build" targets
are active, all the other targets are no-op. When make is run outside
of the container, it's the opposite, except for the "build" targets
which all depend on this .any-build timestamp file to trigger the
container build execution.

The targets dependency graph is still complete, so "source" targets
will always all be executed before the container, and configure steps
will optionally run if the generated files are missing. When source
change is detected, only the build rules are executed again, trusting
each build system to decide if configure should be run again or not.

build/makefile_base.mak

@@ -1,3 +1,6 @@
+SRC := $(abspath $(SRCDIR))
+OBJ := $(abspath $(CURDIR))
+
 ##
 ## Nested make
 ##
@@ -89,6 +92,30 @@ CONTAINER_SHELL := $(SHELL)
 STEAM_RUNTIME_RUNSH :=
 endif
 
+
+MAKECMDGOALS32 := $(filter-out all32,$(filter %32,$(MAKECMDGOALS)))
+MAKECMDGOALS64 := $(filter-out all64,$(filter %64,$(MAKECMDGOALS)))
+
+all: all32 all64
+.PHONY: all
+
+all32 $(MAKECMDGOALS32):
+.PHONY: all32 $(MAKECMDGOALS32)
+
+all32 $(MAKECMDGOALS64):
+.PHONY: all64 $(MAKECMDGOALS64)
+
+ifeq ($(CONTAINER),)
+container-build: private SHELL := $(CONTAINER_SHELL)
+container-build:
+	+$(MAKE) -f $(firstword $(MAKEFILE_LIST)) $(MFLAGS) $(MAKEOVERRIDES) CONTAINER=1 $(MAKECMDGOALS32) $(MAKECMDGOALS64)
+.PHONY: container-build
+
+all32 $(MAKECMDGOALS32): container-build
+all64 $(MAKECMDGOALS64): container-build
+endif
+
+
 .PHONY: test-container
 test-container:
 	@echo >&2 ":: Testing container"
@@ -268,6 +295,7 @@ OBJ_DIRS := $(TOOLS_DIR32)        $(TOOLS_DIR64)        \
 $(OBJ_DIRS):
 	mkdir -p $@
 
+ifeq ($(CONTAINER),)
 
 ## downloads -- Convenience target to download packages used during the build
 ## process. Places them in subdirs one up from the Proton source dir, so
@@ -471,6 +499,8 @@ module64:
 
 module: module32 module64
 
+endif # ifeq ($(CONTAINER),)
+
 GST_COMMON_MESON_ARGS := \
 	-Dexamples=disabled \
 	-Dtests=disabled \
@@ -1528,6 +1558,7 @@ mediaconv64: $(MAKEFILE_DEP) gstreamer64 | $(MEDIACONV_OBJ64)
 
 mediaconv: mediaconv32 mediaconv64
 
+ifeq ($(CONTAINER),)
 ALL_TARGETS += fonts
 GOAL_TARGETS += fonts
 
@@ -1668,4 +1699,5 @@ all32_configure: $(GOAL_TARGETS_CONFIGURE32)
 all64_configure: $(GOAL_TARGETS_CONFIGURE64)
 	@echo ":: make $@ succeeded"
 
+endif # ifeq ($(CONTAINER),)
 endif # End of NESTED_MAKE from beginning