[Libomptarget] Remove undefined symbol in old runtime

[jhuber6]

Summary

A function with no definition was left in the old runtime, causing
linker errors when trying to compile.

[tianshilei1992]

Yeah, I saw this once.

openmp/libomptarget/deviceRTLs/target_interface.h

 
 // Calls to the NVPTX layer (assuming 1D layout)
 EXTERN int __kmpc_get_hardware_thread_id_in_block();
 EXTERN int GetBlockIdInKernel();
 EXTERN NOINLINE int __kmpc_get_hardware_num_blocks();
 EXTERN NOINLINE int __kmpc_get_hardware_num_threads_in_block();
 EXTERN unsigned __kmpc_get_warp_size();
 EXTERN unsigned GetWarpId();
-EXTERN unsigned GetWarpSize();
 EXTERN unsigned GetLaneId();
 
 // Atomics
 uint32_t __kmpc_atomic_add(uint32_t *, uint32_t);
 uint32_t __kmpc_atomic_inc(uint32_t *, uint32_t);
 uint32_t __kmpc_atomic_max(uint32_t *, uint32_t);
 uint32_t __kmpc_atomic_exchange(uint32_t *, uint32_t);
 uint32_t __kmpc_atomic_cas(uint32_t *, uint32_t, uint32_t);