Use correct TLS codepath for linker

Replicate ARM libc build's HAVE_ARM_TLS_REGISTER preprocessor definition
logic, to ensure that the runtime linker uses the correct codepath for
accessing the TLS address
diff --git a/linker/Android.mk b/linker/Android.mk
index 6c26eb3..c2d369e 100644
--- a/linker/Android.mk
+++ b/linker/Android.mk
@@ -27,7 +27,11 @@
 LOCAL_CFLAGS += -DLINKER_AREA_SIZE=$(LINKER_AREA_SIZE)
 
 # we need to access the Bionic private header <bionic_tls.h>
-# in the linker
+# in the linker; duplicate the HAVE_ARM_TLS_REGISTER definition
+# from the libc build
+ifeq ($(TARGET_ARCH)-$(ARCH_ARM_HAVE_TLS_REGISTER),arm-true)
+    LOCAL_CFLAGS += -DHAVE_ARM_TLS_REGISTER
+endif
 LOCAL_CFLAGS += -I$(LOCAL_PATH)/../libc/private
 
 ifeq ($(TARGET_ARCH),arm)