The whole system (/usr/bin/crt0.o for example) is long-branch compiled,
so *any* linkage operation causes this warning to be raised.  Don't do
it.

--- ld/MachOReaderRelocatable.hpp
+++ ld/MachOReaderRelocatable.hpp
@@ -4165,8 +4165,6 @@
 				if ( nextReloc->r_type() != PPC_RELOC_PAIR ) {
 					throw "PPC_RELOC_JBSR missing following pair";
 				}
-				if ( !fHasLongBranchStubs )
-					warning("object file compiled with -mlong-branch which is no longer needed. To remove this warning, recompile without -mlong-branch: %s", fPath);
 				fHasLongBranchStubs = true;
 				result = true;
 				if ( reloc->r_extern() ) {