fix broken AMD OpenCL compile

The AMD compiler for OpenCL shipped with the driver 14XX is broken
and can not compile xmr-stak since the monero v8 changes are introduced.

- workaround a simple compare.
- add new device define `OPENCL_DRIVER_MAJOR`

xmrstak/backend/amd/amd_gpu/gpu.cpp

@@ -420,6 +420,11 @@ size_t InitOpenCLGpu(cl_context opencl_ctx, GpuContext* ctx, const char* source_
 		options += " -DMEMORY=" + std::to_string(hashMemSize);
 		options += " -DALGO=" + std::to_string(miner_algo[ii]);
 		options += " -DCN_UNROLL=" + std::to_string(ctx->unroll);
+		/* AMD driver output is something like: `1445.5 (VM)`
+		 * and is mapped to `14` only. The value is only used for a compiler
+		 * workaround.
+		 */
+		options += " -DOPENCL_DRIVER_MAJOR=" + std::to_string(std::stoi(openCLDriverVer.data()) / 100);
 
 		/* create a hash for the compile time cache
 		 * used data:

xmrstak/backend/amd/amd_gpu/opencl/fast_int_math_v2.cl

@@ -2,6 +2,10 @@ R"===(
 /*
  * @author SChernykh
  */
+
+// cryptonight_monero_v8
+#if(ALGO==11)
+
 static const __constant uint RCP_C[256] =
 {
 	0xfe01be73u,0xfd07ff01u,0xfa118c5au,0xf924fb13u,0xf630cddbu,0xf558f73cu,0xf25f2934u,0xf1a3f37bu,
@@ -68,9 +72,19 @@ inline uint2 fast_div_v2(const __local uint *RCP, ulong a, uint b)
 	const ulong k = mul_hi(as_uint2(a).s0, r) + ((ulong)(r) * as_uint2(a).s1) + a;
 
 	ulong q;
-	((uint*)&q)[0] = as_uint2(k).s1;;
-	((uint*)&q)[1] = (k < a) ? 1 : 0;
-
+	((uint*)&q)[0] = as_uint2(k).s1;
+
+#if defined(cl_amd_device_attribute_query) && (OPENCL_DRIVER_MAJOR == 14)
+	/* The AMD driver 14.XX is not able to compile `(k < a)`
+	 * https://github.com/fireice-uk/xmr-stak/issues/1922
+	 * This is a workaround for the broken compiler.
+	 */
+	const long xx = k - a;
+	((uint*)&q)[1] = (xx < 0) ? 1U : 0U;
+#else
+	((uint*)&q)[1] = (k < a) ? 1U : 0U;
+#endif
+	
 	const long tmp = a - q * b;
 	const bool overshoot = (tmp < 0);
 	const bool undershoot = (tmp >= b);
@@ -105,4 +119,7 @@ inline uint fast_sqrt_v2(const ulong n1)
 
 	return result;
 }
+
+#endif
+
 )==="