Fixes for basic explicit_s2v and commonfns degrees for cl_half (#2024)

Basic explicit_s2v:

The verification step was always using round to even when converting a
float to half even for round to zero cores.

Commonfns degrees:

The verification step was only taking into account infinities and not
values that over/underflow. This resulted in an incorrect error
calculation. E.g:

double cpu_result = 175668.85998711039;
cl_half gpu_result = 31743; // this is 65504 when converting to float,
we overflowed.
float error = (cpu_result - gpu_result) * some_factor;

The fix adds the check if( (cl_half) reference == test ) before
calculating the error.

test_common/harness/conversions.h

@@ -25,6 +25,8 @@
 #include <string.h>
 #include <sys/types.h>
 
+#include <CL/cl_half.h>
+
 /* Note: the next three all have to match in size and order!! */
 
 enum ExplicitTypes
@@ -71,6 +73,7 @@ extern const char *get_explicit_type_name(ExplicitType type);
 extern void convert_explicit_value(void *inRaw, void *outRaw,
                                    ExplicitType inType, bool saturate,
                                    RoundingType roundType,
+                                   cl_half_rounding_mode halfRoundingMode,
                                    ExplicitType outType);
 
 extern void generate_random_data(ExplicitType type, size_t count, MTdata d,