Documentation: -gsplit-dwarf missing from Option Summary

[Stephan Bergmann]

Cannot identify what sorting is used for that list (if any), so putting 
it at the end (and -gsplit-dwarf also follows -fvar-tracking-assignments 
in the "Options for Debugging Your Program" section).

Author: Stephan Bergmann <sberg...@redhat.com>
Date:   Tue Jun 26 15:04:54 2018 +0200

    Documentation: -gsplit-dwarf missing from Option Summary

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f231da3cde2..3f74b9ac336 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -360,7 +360,7 @@ Objective-C and Objective-C++ Dialects}.
 -femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
 -feliminate-unused-debug-symbols  -femit-class-debug-always @gol
 -fno-merge-debug-strings  -fno-dwarf2-cfi-asm @gol
--fvar-tracking  -fvar-tracking-assignments}
+-fvar-tracking  -fvar-tracking-assignments -gsplit-dwarf}

 @item Optimization Options
 @xref{Optimize Options,,Options that Control Optimization}.