package/ti-sgx-um: new package

package/ti-sgx-um: new package

This package adds the userspace libraries for the SGX graphics
accelerator of the following Texas Instruments SoCs: AM335x, AM437x,
AM4430, AM5430 It also adds a config file for the libraries and a
System-V init script.

Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
[Thomas:
 - Add Config.in comment about the ti-sgx-km dependency.
 - Add dependency on glibc since the package consists of pre-built
   libraries that can only work with glibc.
 - Add Config.in comment about thread and glibc dependencies
 - Use tabs for indentation everywhere.
 - Use git:// instead of http:// to clone, since http:// doesn't work.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>