build: Add minimal Makefile

Add a basic `Makefile` to allow a runtime to be built:

- Clear Containers-based Kata runtime:
  ```
  $ make KATA_RUNTIME=cc [install]
  ```

- `runv`-based Kata runtime:
  ```
  $ make KATA_RUNTIME=runv [install]
  ```

Fixes #15.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

Makefile

@@ -0,0 +1,82 @@
+#
+# Copyright (c) 2018 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+DESTBINDIR = /usr/local/bin
+
+KATA_RUNTIME_NAME = kata-runtime
+KATA_RUNTIME_PATH = $(DESTBINDIR)/$(KATA_RUNTIME_NAME)
+
+ifeq (,$(KATA_RUNTIME))
+    # no argument specified
+    ifeq (,$(MAKECMDGOALS))
+        fail = true
+    endif
+
+    # remove goals that don't require the variable to be set
+    remaining=$(filter-out help,$(MAKECMDGOALS))
+
+    ifneq (,$(remaining))
+        fail = true
+    endif
+
+    ifeq ($(fail),true)
+        $(error "ERROR: KATA_RUNTIME not set - run 'make help'")
+    endif
+endif
+
+ifeq (cc,$(KATA_RUNTIME))
+	RUNTIME_DIR = cc-runtime
+	RUNTIME_NAME = kata-runtime-cc
+	TARGET = $(RUNTIME_NAME)
+	DESTTARGET = $(DESTBINDIR)/$(TARGET)
+endif
+
+ifeq (runv,$(KATA_RUNTIME))
+	RUNTIME_DIR = runv
+	RUNTIME_NAME = runv
+	DESTTARGET = $(DESTBINDIR)/$(RUNTIME_NAME)
+endif
+
+default: build
+
+build:
+ifeq (cc,$(KATA_RUNTIME))
+	make -C $(RUNTIME_DIR) build-kata-system TARGET=$(TARGET) DESTTARGET=$(DESTTARGET)
+endif
+ifeq (runv,$(KATA_RUNTIME))
+	(cd $(RUNTIME_DIR) && [ -e configure ] || ./autogen.sh && ./configure && make)
+endif
+
+install: install-runtime create-symlink
+
+install-runtime:
+ifeq (cc,$(KATA_RUNTIME))
+	make -C $(RUNTIME_DIR) install-kata-system TARGET=$(TARGET) DESTTARGET=$(DESTTARGET)
+endif
+ifeq (runv,$(KATA_RUNTIME))
+	make -C $(RUNTIME_DIR) install
+endif
+
+create-symlink:
+	ln -s $(DESTTARGET) $(KATA_RUNTIME_PATH)
+
+remove-symlink:
+	rm -f $(KATA_RUNTIME_PATH)
+
+clean: remove-symlink
+ifeq (cc,$(KATA_RUNTIME))
+	make -C $(RUNTIME_DIR) clean TARGET=$(TARGET)
+endif
+ifeq (runv,$(KATA_RUNTIME))
+	make -C $(RUNTIME_DIR) clean
+endif
+
+help:
+	@printf "To build a Kata Containers runtime:\n"
+	@printf "\n"
+	@printf "  \$$ make KATA_RUNTIME={cc|runv} [install]\n"
+	@printf "\n"
+	@printf "Project home: https://github.com/kata-containers\n"