Add a separate version of the docs build that only does the stubs.

That way we don't have to wait for clearsilver to write the thousands
of html files during every build.

(This is the build change, there is also a frameworks/base change)

core/main.mk

@@ -400,8 +400,6 @@ ifeq ($(BUILD_TINY_ANDROID), true)
 # TINY_ANDROID is a super-minimal build configuration, handy for board 
 # bringup and very low level debugging
 
-INTERNAL_DEFAULT_DOCS_TARGETS := 
-
 subdirs := \
 	bionic \
 	system/core \
@@ -420,7 +418,6 @@ else	# !BUILD_TINY_ANDROID
 #
 # Typical build; include any Android.mk files we can find.
 #
-INTERNAL_DEFAULT_DOCS_TARGETS := offline-sdk-docs
 subdirs := $(TOP)
 
 FULL_BUILD := true
@@ -449,7 +446,6 @@ include $(ONE_SHOT_MAKEFILE)
 # would have been with a normal make.
 CUSTOM_MODULES := $(sort $(call get-tagged-modules,$(ALL_MODULE_TAGS),))
 FULL_BUILD :=
-INTERNAL_DEFAULT_DOCS_TARGETS :=
 # Stub out the notice targets, which probably aren't defined
 # when using ONE_SHOT_MAKEFILE.
 NOTICE-HOST-%: ;
@@ -657,7 +653,6 @@ droidcore: files \
 	$(INSTALLED_BOOTIMAGE_TARGET) \
 	$(INSTALLED_RECOVERYIMAGE_TARGET) \
 	$(INSTALLED_USERDATAIMAGE_TARGET) \
-	$(INTERNAL_DEFAULT_DOCS_TARGETS) \
 	$(INSTALLED_FILES_FILE)
 
 # The actual files built by the droidcore target changes depending