examples: move api/ and standalone/ entry to examples/Makefile

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/examples/Makefile b/examples/Makefile
new file mode 100644
index 0000000..18d008e
--- /dev/null
+++ b/examples/Makefile
@@ -0,0 +1,9 @@
+ifndef CONFIG_SANDBOX
+
+ifdef FTRACE
+subdir-ccflags-y += -finstrument-functions -DFTRACE
+endif
+
+subdir-y += standalone
+subdir-$(CONFIG_API) += api
+endif