Introduce TARGET_BUILD_UNBUNDLED.

Setting this flag enables unbundled building, i.e. without support for
building the system image and other platform targets. This
functionality was previously enabled by TARGET_BUILD_APPS, and setting
that still implies TARGET_BUILD_UNBUNDLED.

This helps unbundled builds that aren't apps, e.g. ART runtest builds.
Specifically, with the topic of the child CL
https://r.android.com/1324517 TARGET_BUILD_UNBUNDLED does not imply
disabling dexpreopting, unlike TARGET_BUILD_APPS.

TODO: There may still be app-specific conditions that are incorrectly
controlled by TARGET_BUILD_UNBUNDLED, in particular on the Soong side
through config.UnbundledBuild().

Test: Flash & boot
Test: TH, in particular builds green on ub-launcher3-master
Bug: 157549171
Change-Id: Ic09fc879117ee06cab5444edfc280ed2b52d2870
diff --git a/core/Makefile b/core/Makefile
index 561368d..ae28300 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -130,7 +130,7 @@
 
 # -----------------------------------------------------------------
 # docs/index.html
-ifeq (,$(TARGET_BUILD_APPS))
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 gen := $(OUT_DOCS)/index.html
 ALL_DOCS += $(gen)
 $(gen): frameworks/base/docs/docs-redirect-index.html
@@ -3306,7 +3306,7 @@
 # -----------------------------------------------------------------
 # Check VINTF of build
 
-ifndef TARGET_BUILD_APPS
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 intermediates := $(call intermediates-dir-for,PACKAGING,check_vintf_all)
 check_vintf_all_deps :=
 
@@ -3512,13 +3512,12 @@
 check_vintf_common_srcs :=
 check_vintf_all_deps :=
 intermediates :=
-endif # !TARGET_BUILD_APPS
+endif # !TARGET_BUILD_UNBUNDLED
 
 # -----------------------------------------------------------------
 # Check image sizes <= size of super partition
 
-ifeq (,$(TARGET_BUILD_APPS))
-# Do not check for apps-only build
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 
 ifeq (true,$(PRODUCT_BUILD_SUPER_PARTITION))
 
@@ -3554,7 +3553,7 @@
 
 endif # PRODUCT_BUILD_SUPER_PARTITION
 
-endif # TARGET_BUILD_APPS
+endif # !TARGET_BUILD_UNBUNDLED
 
 # -----------------------------------------------------------------
 # bring in the installer image generation defines if necessary
@@ -4481,7 +4480,7 @@
 # A zip of the appcompat directory containing logs
 APPCOMPAT_ZIP := $(PRODUCT_OUT)/appcompat.zip
 # For apps_only build we'll establish the dependency later in build/make/core/main.mk.
-ifndef TARGET_BUILD_APPS
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 $(APPCOMPAT_ZIP): $(INSTALLED_SYSTEMIMAGE_TARGET) \
 	    $(INSTALLED_RAMDISK_TARGET) \
 	    $(INSTALLED_BOOTIMAGE_TARGET) \
@@ -4510,7 +4509,7 @@
 
 SYMBOLS_ZIP := $(PRODUCT_OUT)/$(name).zip
 # For apps_only build we'll establish the dependency later in build/make/core/main.mk.
-ifndef TARGET_BUILD_APPS
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 $(SYMBOLS_ZIP): $(INSTALLED_SYSTEMIMAGE_TARGET) \
 	    $(INSTALLED_RAMDISK_TARGET) \
 	    $(INSTALLED_BOOTIMAGE_TARGET) \
@@ -4536,7 +4535,7 @@
 name := $(name)_debug
 endif
 COVERAGE_ZIP := $(PRODUCT_OUT)/$(name).zip
-ifndef TARGET_BUILD_APPS
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 $(COVERAGE_ZIP): $(INSTALLED_SYSTEMIMAGE_TARGET) \
 	    $(INSTALLED_RAMDISK_TARGET) \
 	    $(INSTALLED_BOOTIMAGE_TARGET) \
@@ -4611,7 +4610,7 @@
 #
 PROGUARD_DICT_ZIP := $(PRODUCT_OUT)/$(TARGET_PRODUCT)-proguard-dict-$(FILE_NAME_TAG).zip
 # For apps_only build we'll establish the dependency later in build/make/core/main.mk.
-ifndef TARGET_BUILD_APPS
+ifeq (,$(TARGET_BUILD_UNBUNDLED))
 $(PROGUARD_DICT_ZIP): \
     $(INSTALLED_SYSTEMIMAGE_TARGET) \
     $(INSTALLED_RAMDISK_TARGET) \