mk: introduce rte.extsubdir.mk for projects with subdirectories

This makefile can be included by a project that needs to build several
applications or libraries that are located in different directories.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

mk/rte.extsubdir.mk

@@ -0,0 +1,53 @@
+#   BSD LICENSE
+#
+#   Copyright(c) 2014 6WIND S.A.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of 6WIND S.A. nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+MAKEFLAGS += --no-print-directory
+
+# output directory
+O ?= .
+BASE_OUTPUT ?= $(O)
+CUR_SUBDIR ?= .
+
+.PHONY: all
+all: $(DIRS-y)
+
+.PHONY: clean
+clean: $(DIRS-y)
+
+.PHONY: $(DIRS-y)
+$(DIRS-y):
+	@echo "== $@"
+	$(Q)$(MAKE) -C $(@) \
+		M=$(CURDIR)/$(@)/Makefile \
+		O=$(BASE_OUTPUT)/$(CUR_SUBDIR)/$(@)/$(RTE_TARGET) \
+		BASE_OUTPUT=$(BASE_OUTPUT) \
+		CUR_SUBDIR=$(CUR_SUBDIR)/$(@) \
+		S=$(CURDIR)/$(@) \
+		$(filter-out $(DIRS-y),$(MAKECMDGOALS))