Fixing compile errors when compiling with clang++

[daniela-hase]

This PR fixes compile errors when compiling cuBQL with clang++.

Original error messages were:

cuBQL/builder/cuda/sah_builder.h:68:20: error: variable length arrays in C++ are a Clang extension [-Werror,-Wvla-cxx-extension]
   68 |       float rAreas[sah.numBins];

cuBQL/builder/cuda/radix.h:588:11: error: no matching function for call to 'min'
  588 |         ? min(buildConfig.makeLeafThreshold,buildConfig.maxAllowedLeafSize)

cuBQL/builder/cuda/builder_common.h:166:45: error: array index 3 is past the end of the array (that has type 'const typename int_type_of<scalar_t>::type[3]' (aka 'const int[3]')) [-Werror,-Warray-bounds]
  166 |                                   ?((dim>2)?lower[3]:lower[2])
      |                                             ^     ~

cuBQL/builder/cuda/builder_common.h:97:22: error: no matching function for call to '__float_as_int'
   97 |       int32_t bits = __float_as_int(f);
      |                      ^~~~~~~~~~~~~~