skip re-reading defaults from txi-en.tex

git-svn-id: https://svn.r-project.org/R/trunk@88383 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: smeyer

doc/manual/R-defs.texi

@@ -1,4 +1,7 @@
+@ifnottex
+@c work around incomplete texinfo.tex packaging without txi-en.tex
 @documentlanguage en
+@end ifnottex
 @documentencoding UTF-8
 
 @macro R{}