doc/texi2pod: fix an unescaped left brace

This silences some deprecation warnings

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>

doc/texi2pod.pl

@@ -384,7 +384,7 @@ sub postprocess
     # @* is also impossible in .pod; we discard it and any newline that
     # follows it.  Similarly, our macro @gol must be discarded.
 
-    s/\@anchor{(?:[^\}]*)\}//g;
+    s/\@anchor\{(?:[^\}]*)\}//g;
     s/\(?\@xref\{(?:[^\}]*)\}(?:[^.<]|(?:<[^<>]*>))*\.\)?//g;
     s/\s+\(\@pxref\{(?:[^\}]*)\}\)//g;
     s/;\s+\@pxref\{(?:[^\}]*)\}//g;