external/fec: fix host library on Mac

Disable LOCAL_SANITIZE := integer on Mac due to compatibility issues.

Change-Id: I6f2ad3fc26a10f78cd19cef3e33ac1ada22e7741
diff --git a/Android.mk b/Android.mk
index 027baef..88fa518 100644
--- a/Android.mk
+++ b/Android.mk
@@ -15,7 +15,9 @@
 LOCAL_MODULE := libfec_rs_host
 LOCAL_CLANG := true
 LOCAL_CFLAGS := -Wall -O3
+ifeq ($(HOST_OS),linux)
 LOCAL_SANITIZE := integer
+endif
 LOCAL_SRC_FILES := \
 	encode_rs_char.c \
 	decode_rs_char.c \