Add optif9 to the experimental API for use by nlme.

git-svn-id: https://svn.r-project.org/R/trunk@88927 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: luke

doc/manual/R-exts.texi

@@ -16561,6 +16561,11 @@ be found from the help page for @code{optim}: see the source code
 @file{src/appl/lbfgsb.c} for the values of @code{nbd}, which
 specifies which bounds are to be used.
 
+The function @code{optif9} is included in the experimental API for use
+by the @pkg{nlme} package. It is subject to change and not intended for
+use by other packages.
+@eapifun optif9
+
 
 @node Integration
 @section Integration