Add sync_file_range to <fcntl.h>.

Bug: http://b/27952303
Change-Id: Idadfacd657ed415abc11684b9471e4e24c2fbf05
diff --git a/libc/libc.arm.map b/libc/libc.arm.map
index 9890b14..40f645c 100644
--- a/libc/libc.arm.map
+++ b/libc/libc.arm.map
@@ -1283,6 +1283,7 @@
     sigpause;
     sigrelse;
     sigset;
+    sync_file_range;
 } LIBC_N;
 
 LIBC_PRIVATE {