In cross compiling, one normally assumes that the user supplied sysroot contains all of the libraries needed in the link. And so the linker adjusts the -L paths to look in the sysroot.
However because libclang_rt.* is supplied at link time as a full path, the link can not find it in the sysroot.
This change will churn the user's current experience and the unit tests.
I will take take of the tests, if folks are ok with the change.