Delete UnknownAddress. It is a perfectly valid symbol value.

getSymbolValue now returns a value that in convenient for most callers:
* 0 for undefined
* symbol size for common symbols
* offset/address for symbols the rest

Code that needs something more specific can check getSymbolFlags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241605 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Object/SymbolicFile.h

@@ -115,8 +115,6 @@ public:
 
 typedef content_iterator<BasicSymbolRef> basic_symbol_iterator;
 
-const uint64_t UnknownAddress = ~0ULL;
-
 class SymbolicFile : public Binary {
 public:
   ~SymbolicFile() override;