use macro to link ldso to libpthread, so it gets the the right name on 64 bit archs

Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

libpthread/nptl/Makefile.in

@@ -220,7 +220,7 @@ else
 LDFLAGS-libpthread.so := $(LDFLAGS)
 endif
 
-LDFLAGS-libpthread.so += $(top_builddir)lib/ld-uClibc-$(VERSION).so $(top_builddir)lib/libdl-$(VERSION).so
+LDFLAGS-libpthread.so += $(top_builddir)lib/$(UCLIBC_LDSO_NAME)-$(VERSION).so $(top_builddir)lib/libdl-$(VERSION).so
 
 LIBS-libpthread.so := $(LIBS)