Issue #42 — Multilib: --no-warn-search-mismatch.

Pass -Xlinker before every additional linker switch, so gcc will,
in its turn, pass the switch to ld.

gen/linker.cpp

@@ -301,6 +301,7 @@ int linkObjToBinary(bool sharedLib)
     for (unsigned i = 0; i < global.params.linkswitches->dim; i++)
     {
         char *p = (char *)global.params.linkswitches->data[i];
+        args.push_back("-Xlinker");
         args.push_back(p);
     }