[gcc r11-6775] aix: document dwarf 4 default (and TPF default)

[David Edelsohn]

https://gcc.gnu.org/g:f56e14101b9f808b4cdded9bf6900b2ec4b1417a

commit r11-6775-gf56e14101b9f808b4cdded9bf6900b2ec4b1417a
Author: David Edelsohn <dje.gcc@gmail.com>
Date:   Mon Jan 18 13:09:28 2021 -0500

    aix: document dwarf 4 default (and TPF default)
    
    gcc/ChangeLog:
    
            * doc/invoke.texi (-gdwarf): TPF defaults to version 2 and AIX
            defaults to version 4.

Diff:
---
 gcc/doc/invoke.texi | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 5077ea7df13..5f4a06625eb 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -9613,8 +9613,9 @@ possible.
 @opindex gdwarf
 Produce debugging information in DWARF format (if that is supported).
 The value of @var{version} may be either 2, 3, 4 or 5; the default
-version for most targets is 5 (with the exception of VxWorks and
-Darwin/Mac OS X which default to version 2).
+version for most targets is 5 (with the exception of VxWorks, TPF and
+Darwin/Mac OS X, which default to version 2, and AIX, which defaults
+to version 4).
 
 Note that with DWARF Version 2, some ports require and always
 use some non-conflicting DWARF 3 extensions in the unwind tables.