Add __gdtoa to the list of FreeBSD private symbols. Unfortunately,

this is used by some 3rd party applications when {e,f,g}cvt() are
not found.  POSIX defines the xcvt() funtions but says they are
deprecated in favor or sprintf().  We'll import these functions
from OpenBSD and remove __gdtoa() from the exported interfaces
when libc version is bumped.

lib/libc/gdtoa/Symbol.map

@@ -37,3 +37,7 @@ FBSD_1.0 {
 	# FreeBSD additions
 	strtold;
 };
+
+FBSDprivate {
+	__gdtoa;
+};