build: General build refactoring

Add vars.mk for variable sharing across makefiles.
Stub and rename example YAML file and template.
  Content to be re-introduced as support is added.
Move generated C++ to a header file.
Add input YAML path option to configure.

Change-Id: Ia06e392e8b120b1e1d8614046064fa432a6f9e18
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/configure.ac b/configure.ac
index 38e8d79..e738f3f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -50,5 +50,8 @@
     AC_SUBST([OESDK_TESTCASE_FLAGS], [$testcase_flags])
 )
 
+AC_ARG_VAR(YAML_PATH, [The path to the yaml config files.])
+AS_IF([test "x$YAML_PATH" == "x"], [YAML_PATH="$srcdir/example"])
+
 AC_CONFIG_FILES([Makefile src/Makefile])
 AC_OUTPUT