VPP-94: Add build-data directory for plugins and Makefile target

Commit e36af5f315 moved sample-plugin a dedicated directory.
The build system could not find sources for sample-plugin-* targets.
This commit adds a dedicated build-data/packages directory for
plugins and moves sample-plugin.mk there.

Change-Id: I9e3ee8858580e86ff6d4f7317300df0a5e239a01
Signed-off-by: Pierre Pfister <ppfister@cisco.com>

Makefile

@@ -106,7 +106,7 @@ ifeq ($(OS_ID),ubuntu)
 	fi ; \
 	exit 0
 endif
-	@echo "SOURCE_PATH = $(WS_ROOT)"                   > $(BR)/build-config.mk
+	@echo "SOURCE_PATH = $(WS_ROOT) $(WS_ROOT)/plugins"> $(BR)/build-config.mk
 	@echo "#!/bin/bash\n"                              > $(BR)/path_setup
 	@echo 'export PATH=$(BR)/tools/ccache-bin:$$PATH' >> $(BR)/path_setup
 	@echo 'export PATH=$(BR)/tools/bin:$$PATH'        >> $(BR)/path_setup
@@ -162,6 +162,12 @@ wipe-release: $(BR)/.bootstrap.ok
 
 rebuild-release: wipe-release build-release
 
+plugins: $(BR)/.bootstrap.ok
+	$(call make,$(PLATFORM)_debug,sample-plugin-install)
+
+plugins-release: $(BR)/.bootstrap.ok
+	$(call make,$(PLATFORM),sample-plugin-install)
+
 STARTUP_DIR ?= $(PWD)
 ifeq ("$(wildcard $(STARTUP_CONF))","")
 define run

build-root/bootstrap.sh

@@ -12,7 +12,7 @@ ADD_TO_PATH="$build_root/tools/ccache-bin:$build_root/tools/bin"
 
 # Construct build-config.mk
 cd $build_root
-echo SOURCE_PATH = $wsroot > build-config.mk
+echo SOURCE_PATH = $wsroot $wsroot/plugins/ > build-config.mk
 echo 
 echo Saving PATH settings in `pwd`/path_setup
 echo Source this file later, as needed