i#1569 AArch64: Make ELF_R_TLS_DESC fail at run time, not load time.
i#1569 AArch64: Make ELF_R_TLS_DESC fail at run time, not load time.

A TLS descriptor contains a pointer to a function that is invoked
lazily to resolve the relocation. Rather than fail when loading a
shared object it is more helpful to fail only if there is an attempt
to resolve the relocation at run time. Sometimes there is no such
attempt.

Review-URL: https://codereview.appspot.com/296650043

AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio