[llvm-jitlink] Add more information about allocation failures.

Slab allocator failures will now report requested size and remaining capacity.

Author: lhames

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

@@ -437,7 +437,12 @@ class JITLinkSlabAllocator final : public JITLinkMemoryManager {
       uint64_t SlabRemainingSize = SlabRemaining.allocatedSize();
 
       if (SegmentSize > SlabRemainingSize)
-        return make_error<StringError>("Slab allocator out of memory",
+        return make_error<StringError>("Slab allocator out of memory: "
+                                       "request for " +
+                                       formatv("{0:x}", SegmentSize) +
+                                       " bytes exceeds remaining capacity of " +
+                                       formatv("{0:x}", SlabRemainingSize) +
+                                       " bytes",
                                        inconvertibleErrorCode());
 
       sys::MemoryBlock SegMem(SlabBase, SegmentSize);