Bug 1101070 - Add missing OSX build flag for the new replace-malloc symbol. r=njn,r=khuey

Bug 818922 added a new replace-malloc symbol that the OSX linker tricks need
to know about.

mozglue/build/replace_malloc.mk

@@ -5,6 +5,7 @@
 ifeq (Darwin_1,$(OS_TARGET)_$(MOZ_REPLACE_MALLOC))
 OS_LDFLAGS += \
   -Wl,-U,_replace_init \
+  -Wl,-U,_replace_get_bridge \
   -Wl,-U,_replace_malloc \
   -Wl,-U,_replace_posix_memalign \
   -Wl,-U,_replace_aligned_alloc \