[MIPS] Fix Mips64 build of libm

Change-Id: Ib742b408d4f21d5ec8d455a3fea7c08165c7f321
diff --git a/libm/Android.mk b/libm/Android.mk
index f27c62e..dc6c704 100644
--- a/libm/Android.mk
+++ b/libm/Android.mk
@@ -270,6 +270,9 @@
 LOCAL_SRC_FILES_mips += \
     mips/fenv.c \
 
+LOCAL_SRC_FILES_mips64 += \
+    mips/fenv.c \
+
 LOCAL_SRC_FILES_x86 += \
     i387/fenv.c \