Error CL_BUILD_PROGRAM_FAILURE & CL_INVALID_KERNEL
Hi,

Got this issue with xmrig-amd on my Mac and I have no idea what causes it.

```
~/xmrig-amd/build$ ./xmrig-amd 
 * ABOUT        XMRig-AMD/2.14.0 clang/10.0.0
 * LIBS         libuv/1.26.0 OpenCL/1.2 OpenSSL/1.0.2q microhttpd/0.9.62 
 * CPU          Intel(R) Core(TM) i7-7920HQ CPU @ 3.10GHz x64 AES
 * ALGO         cryptonight, donate=1%
 * POOL #1      pool.supportxmr.com:3333 variant auto
 * COMMANDS     hashrate, pause, resume
[2019-03-12 15:51:05] compiling code and initializing GPUs. This will take a while...
[2019-03-12 15:51:05] #00, GPU #01 AMD Radeon Pro 560 Compute Engine, i:192 (8/256), si:2/2, u:8, cu:16
[2019-03-12 15:51:05]              0.38/1.00/4 GB
[2019-03-12 15:51:05] #01, GPU #01 AMD Radeon Pro 560 Compute Engine, i:192 (8/256), si:2/2, u:8, cu:16
[2019-03-12 15:51:05]              0.38/1.00/4 GB
[2019-03-12 15:51:05] use pool pool.supportxmr.com:3333  178.63.100.197 
[2019-03-12 15:51:05] new job from pool.supportxmr.com:3333 diff 5000 algo cn/r height 1789131
[2019-03-12 15:51:12] new job from pool.supportxmr.com:3333 diff 8108 algo cn/r height 1789131
[2019-03-12 15:51:15] Error CL_BUILD_PROGRAM_FAILURE when calling clBuildProgram.
[2019-03-12 15:51:15] CryptonightR: clBuildProgram returned error CL_BUILD_PROGRAM_FAILURE
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clSetKernelArg for kernel 20, argument 0.
[2019-03-12 15:51:15] Error CL_BUILD_PROGRAM_FAILURE when calling clBuildProgram.
[2019-03-12 15:51:15] CryptonightR: clBuildProgram returned error CL_BUILD_PROGRAM_FAILURE
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clSetKernelArg for kernel 20, argument 0.
[2019-03-12 15:51:15] Error CL_BUILD_PROGRAM_FAILURE when calling clBuildProgram.
[2019-03-12 15:51:15] CryptonightR: clBuildProgram returned error CL_BUILD_PROGRAM_FAILURE
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clSetKernelArg for kernel 20, argument 0.
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clEnqueueNDRangeKernel for kernel 1.
[2019-03-12 15:51:15] Error CL_BUILD_PROGRAM_FAILURE when calling clBuildProgram.
[2019-03-12 15:51:15] CryptonightR: clBuildProgram returned error CL_BUILD_PROGRAM_FAILURE
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clSetKernelArg for kernel 20, argument 0.
[2019-03-12 15:51:15] Error CL_INVALID_KERNEL when calling clEnqueueNDRangeKernel for kernel 1.
```