libril: Fix multisim flags

Change-Id: Idb2ea518c115c1dbfbbbbb79094938ce006f40d8
(cherry picked from commit c98cc605c67e950bf14aa9f0d14966382ec45a0c)
diff --git a/ril/libril/Android.mk b/ril/libril/Android.mk
index 7939867..b0f982d 100644
--- a/ril/libril/Android.mk
+++ b/ril/libril/Android.mk
@@ -22,18 +22,21 @@
 LOCAL_STATIC_LIBRARIES := \
     libprotobuf-c-nano-enable_malloc \
 
+LOCAL_CFLAGS :=
+
 ifeq ($(SIM_COUNT), 2)
+    LOCAL_CFLAGS += -DANDROID_MULTI_SIM
     LOCAL_CFLAGS += -DANDROID_SIM_COUNT_2
 endif
 
 ifneq ($(filter xmm6262 xmm6360,$(BOARD_MODEM_TYPE)),)
-LOCAL_CFLAGS := -DMODEM_TYPE_XMM6262
+LOCAL_CFLAGS += -DMODEM_TYPE_XMM6262
 endif
 ifeq ($(BOARD_MODEM_TYPE),xmm6260)
-LOCAL_CFLAGS := -DMODEM_TYPE_XMM6260
+LOCAL_CFLAGS += -DMODEM_TYPE_XMM6260
 endif
 ifneq ($(filter m7450 mdm9x35 ss333 tss310 xmm7260,$(BOARD_MODEM_TYPE)),)
-LOCAL_CFLAGS := -DSAMSUNG_NEXT_GEN_MODEM
+LOCAL_CFLAGS += -DSAMSUNG_NEXT_GEN_MODEM
 endif
 
 ifeq ($(BOARD_MODEM_NEEDS_VIDEO_CALL_FIELD), true)