my first "os5" bare-metal on online-compiler

Revision:
0:4cdcddbd6c3d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os.lib	Sat Jun 15 06:49:03 2019 +0000
@@ -0,0 +1,1 @@
+https://github.com/ARMmbed/mbed-os/#0063e5de32fc575f061244c96ac60c41c07bd2e6