Generic Intrinsic support

We've identified a need for a "generic intrinsics" These intrinsics would be identified through either lifting or pattern matching. Here are few examples are:

• min/max
• floor/ceiling/round
• align/extract_bits/clear_bits
• memcpy

The idea is that we would reserve space in the intrinsic identifier field (maybe by setting the top bit) and these would be for internal use only.

enum BNGenericIntrinsic : uint32_t {
   MIN_INTRINSIC = 0x80000000,
   MAX_INTRINSIC,
   FLOOR_INTRINSIC,
   ...
 };

We would likely want to convert the existing builtin_* synthetic builtins to this new, more extensible, system. This system would need to additionally support cross references. Our current cross reference system is based on a uint64_t which is insufficient for representing a cross reference to something that really doesn't exist within the address space. There are a couple of solutions to this:

• Expand the representation of what our definition of 'memory' is to support these types of situations
• Use a mechanism like relocations use which is essentially a symbolic cross reference. So rather than address-based cross references we'd have ones based on a symbol (+ addend)
• The final not-good option would be to continue to use the synthetic_builtins section which has some unfortunate consequences in some cases.

Start by reviewing the existing builtin_* synthetic builtins and the current uint64_t cross-reference system. Compare the proposed identifier scheme with the three cross-reference options; done requires a decided design for generic intrinsics, including the listed examples, cross references, and migration of existing synthetic builtins.