Edge cases encountered while generating bindings for Hwloc

[JBlaschke]

I am generating the bindings for Hwloc_jll, and I encountered a few edge cases that I thought you might like to know about -- all of these have straightforward workarounds, so this isn't urgent here.

• hwloc.h uses INT_MAX:

  #define HWLOC_TYPE_UNORDERED INT_MAX

  requiring the inclusion of something like:

  const INT_MAX = typemax(Int64)

• hwloc.h defines:

  #define HWLOC_UNKNOWN_INDEX (unsigned)-1

  which Clang.jl translated to:

  const HWLOC_UNKNOWN_INDEX = unsigned - 1 

  I replaced this line with:

  const HWLOC_UNKNOWN_INDEX = INT_MAX

  instead.

• Clang.jl also generated lines like:

  const __HWLOC_HAVE_ATTRIBUTE_UNUSED = GXX_ABOVE_3_4 || GCC_ABOVE_2_95

  However the constants on the RHS are defined as integers, eg:

  const GXX_ABOVE_3_4 = 0
  const GCC_ABOVE_2_95 = 1

  and so on. A quick fix was to replace || with |.

[Gnimuc]

Thanks for the issue. Let's keep collecting those failure cases, so we can fix them in the next round of refactoring.