Admit that dnsmasq relies on BSD extensions.

Change-Id: I926a39980bd4d7475e80a3425c567b7923ede8fa
(cherry picked from commit 8b1654b37f42c6d7c241fdf547d55c0e89aaeb43)

BUG: 28839081
diff --git a/src/Android.mk b/src/Android.mk
index d776d5e..911a07b 100644
--- a/src/Android.mk
+++ b/src/Android.mk
@@ -10,7 +10,7 @@
 
 LOCAL_C_INCLUDES := external/dnsmasq/src
 
-LOCAL_CFLAGS := -O2 -g -W -Wall -D__ANDROID__ -DIPV6 -DNO_TFTP -DNO_SCRIPT
+LOCAL_CFLAGS := -O2 -g -W -Wall -D__ANDROID__ -DIPV6 -DNO_TFTP -DNO_SCRIPT -D_BSD_SOURCE
 LOCAL_SYSTEM_SHARED_LIBRARIES := libc
 LOCAL_SHARED_LIBRARIES := libcutils liblog