Attributes: add a new allocptr attribute

This continues the push away from hard-coded knowledge about functions
towards attributes. We'll use this to annotate free(), realloc() and
cousins and obviate the hard-coded list of free functions.

Differential Revision: https://reviews.llvm.org/D123083

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1538,6 +1538,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::AllocAlign;
   case bitc::ATTR_KIND_ALLOC_SIZE:
     return Attribute::AllocSize;
+  case bitc::ATTR_KIND_ALLOCATED_POINTER:
+    return Attribute::AllocatedPointer;
   case bitc::ATTR_KIND_NO_RED_ZONE:
     return Attribute::NoRedZone;
   case bitc::ATTR_KIND_NO_RETURN: