[JITLink] fix i668 R_386_32 relocation value

Most relocations involve adding the value at the location with a value
taken from elsewhere. This one was missing the addend taken from the
location. Other relocations may be missing this too?

Author: vtjnash

llvm/lib/ExecutionEngine/JITLink/ELF_i386.cpp

@@ -186,6 +186,7 @@ class ELFLinkGraphBuilder_i386 : public ELFLinkGraphBuilder<ELFT> {
     int64_t Addend = 0;
 
     switch (*Kind) {
+    case i386::EdgeKind_i386::Pointer32:
     case i386::EdgeKind_i386::Delta32: {
       const char *FixupContent = BlockToFix.getContent().data() +
                                  (FixupAddress - BlockToFix.getAddress());