Add trivial no-op <nl_types.h>.

Needed to build OpenMP.

Bug: http://b/27617302
Change-Id: Iac15c84ead6f5d5274cfdb2d6d4a4ec0072244bb
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index 49572a0..ed20efc 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1299,6 +1299,9 @@
 
 LIBC_O {
   global:
+    catclose;
+    catgets;
+    catopen;
     getdomainname;
     getsubopt;
     hasmntopt;