[gcc r12-227] doc/install.texi: Document --enable-offload-defaulted config option

[Tobias Burnus <burnus@gcc.gnu.org>]

https://gcc.gnu.org/g:4c84c45d8ab5ef55aabef18da17244dc13170f9c

commit r12-227-g4c84c45d8ab5ef55aabef18da17244dc13170f9c
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Wed Apr 28 21:15:16 2021 +0200

    doc/install.texi: Document --enable-offload-defaulted config option
    
    Document configure --enable-offload-defaulted option added in
    commit r12-218-gfe5bfa6704179f8db7d1ae0b485439e9896df8eb
    
    gcc/ChangeLog:
    
            * doc/install.texi (--enable-offload-defaulted): Document.

Diff:
---
 gcc/doc/install.texi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 4c38244ae58..d2cab15d9fd 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -2239,6 +2239,14 @@ specifying paths @var{path1}, @dots{}, @var{pathN}.
     --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none
 @end smallexample
 
+@item --enable-offload-defaulted
+
+Tell GCC that configured but not installed offload compilers and libgomp
+plugins are silently ignored.  Useful for distribution compilers where
+those are in separate optional packages and where the presence or absence
+of those optional packages should determine the actual supported offloading
+target set rather than the GCC configure-time selection.
+
 @item --with-hsa-runtime=@var{pathname}
 @itemx --with-hsa-runtime-include=@var{pathname}
 @itemx --with-hsa-runtime-lib=@var{pathname}