Implement --allow-multiple-definition.

Patch by George Rimar!

llvm-svn: 248733
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 948d4ec..c57739b 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -139,6 +139,9 @@
   if (Args.hasArg(OPT_noinhibit_exec))
     Config->NoInhibitExec = true;
 
+  if (Args.hasArg(OPT_allow_multiple_definition))
+    Config->AllowMultipleDefinition = true;
+
   // Create a list of input files.
   std::vector<MemoryBufferRef> Inputs;