[oe] prebuilt toolchain versus --sysroot

[Elena Vengerova]

Hello,

I'm trying to use pre-built SDK. PATH, CPPFLAGS and LDFLAGS are correct. 
However configure of the first target package fails because compiler 
cannot find crt1.o. I've found out that it's due --sysroot that points 
to STAGING_DIR_TARGET.

Should I copy SDK libraries and headers to STAGING_DIR_TARGET or there 
is more correct option to resolve this issue?

Thanks,
     Elena