[gcc r12-6963] docs: remove --disable-stage1-checking from requirements

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:3ad29854f0b2b1f468ea87e8cbd2a5c5a72ba5fe

commit r12-6963-g3ad29854f0b2b1f468ea87e8cbd2a5c5a72ba5fe
Author: Martin Liska <mliska@suse.cz>
Date:   Tue Feb 1 16:35:47 2022 +0100

    docs: remove --disable-stage1-checking from requirements
    
    As the minimal GCC version that can build the current master
    is 4.8, it does not make sense mentioning something for older
    versions.
    
    gcc/ChangeLog:
    
            * doc/install.texi: Remove option for GCC < 4.8.

Diff:
---
 gcc/doc/install.texi | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 96b4dfc871a..f4e7dc42198 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -239,11 +239,6 @@ To build all languages in a cross-compiler or other configuration where
 GCC binary (version 4.8 or later) because source code for language
 frontends other than C might use GCC extensions.
 
-Note that to bootstrap GCC with versions of GCC earlier than 4.8, you
-may need to use @option{--disable-stage1-checking}, though
-bootstrapping the compiler with such earlier compilers is strongly
-discouraged.
-
 @item C standard library and headers
 
 In order to build GCC, the C standard library and headers must be present