Merge changes I4e95678f,Ia7c28704,I1bb04bb4,I93d96dca,I50aef5dd into integration

* changes:
  Fix boot failures on some builds linked with ld.lld.
  trusty: generic-arm64-smcall: Support gicr address
  trusty: Allow gic base to be specified with GICD_BASE
  trusty: Allow getting trusty memsize from BL32_MEM_SIZE instead of TSP_SEC_MEM_SIZE
  Fix clang build if CC is not in the path.