Make _scan_nan a bit less visible for libandroid_support users.

Bug: N/A
Test: readelf
Change-Id: Ibb5fbf09f6ae589a3e789107a641013fc6bc375b
diff --git a/libm/freebsd-compat.h b/libm/freebsd-compat.h
index 5bdb9fa..ee41e45 100644
--- a/libm/freebsd-compat.h
+++ b/libm/freebsd-compat.h
@@ -36,4 +36,7 @@
 #define digittoint __libm_digittoint
 int digittoint(char ch);
 
+// Similarly rename _scan_nan.
+#define _scan_nan __libm_scan_nan
+
 #endif