This patch reverts upstream commit b4d3485e4fc1d:

  https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=b4d3485e4fc1d029e620a59deb54b3f4f3f6b209

Otherwise, GCC ends up searching the wrong target directory for cross-headers.

diff --git a/gcc/configure b/gcc/configure
--- a/gcc/configure
+++ b/gcc/configure
@@ -3689,11 +3689,6 @@ esac
 fi
 
 
-# If both --with-sysroot and --with-gxx-include-dir are passed, we interpolate
-# the former in the latter and, upon success, compute gcc_gxx_include_dir as
-# relative to the sysroot.
-gcc_gxx_include_dir_add_sysroot=0
-
 # This logic must match libstdc++-v3/acinclude.m4:GLIBCXX_EXPORT_INSTALL_INFO.
 if test x${gcc_gxx_include_dir} = x; then
   if test x${enable_version_specific_runtime_libs} = xyes; then
@@ -3705,10 +3700,15 @@ if test x${gcc_gxx_include_dir} = x; then
     fi
     gcc_gxx_include_dir="\$(libsubdir)/\$(libsubdir_to_prefix)$libstdcxx_incdir"
   fi
-elif test "${with_sysroot+set}" = set; then
+fi
+
+gcc_gxx_include_dir_add_sysroot=0
+if test "${with_sysroot+set}" = set; then
   gcc_gxx_without_sysroot=`expr "${gcc_gxx_include_dir}" : "${with_sysroot}"'\(.*\)'`
   if test "${gcc_gxx_without_sysroot}"; then
-    gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"
+    if test x${with_sysroot} != x/; then
+      gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"
+    fi
     gcc_gxx_include_dir_add_sysroot=1
   fi
 fi
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 715fcba0482..88136e232df 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -204,11 +204,6 @@ no)	;;
 *)	gcc_gxx_include_dir=$with_gxx_include_dir ;;
 esac])
 
-# If both --with-sysroot and --with-gxx-include-dir are passed, we interpolate
-# the former in the latter and, upon success, compute gcc_gxx_include_dir as
-# relative to the sysroot.
-gcc_gxx_include_dir_add_sysroot=0
-
 # This logic must match libstdc++-v3/acinclude.m4:GLIBCXX_EXPORT_INSTALL_INFO.
 if test x${gcc_gxx_include_dir} = x; then
   if test x${enable_version_specific_runtime_libs} = xyes; then
@@ -220,10 +215,15 @@ if test x${gcc_gxx_include_dir} = x; then
     fi
     gcc_gxx_include_dir="\$(libsubdir)/\$(libsubdir_to_prefix)$libstdcxx_incdir"
   fi
-elif test "${with_sysroot+set}" = set; then
+fi
+
+gcc_gxx_include_dir_add_sysroot=0
+if test "${with_sysroot+set}" = set; then
   gcc_gxx_without_sysroot=`expr "${gcc_gxx_include_dir}" : "${with_sysroot}"'\(.*\)'`
   if test "${gcc_gxx_without_sysroot}"; then
-    gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"
+    if test x${with_sysroot} != x/; then
+      gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"
+    fi
     gcc_gxx_include_dir_add_sysroot=1
   fi
 fi
or</th></tr>
<tr><td><span title='2022-11-02 15:52:19 +0100'>2022-11-02</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=62a3756bd90c922c701e899a6c01c556d8e3c75a'>installer: Skip the backtrace page on user abort.</a><span class='msg-avail'>...<span class='msg-tooltip'>When the user aborts the installation because a core dump is discovered or the
installation command failed, displaying the abort backtrace doesn't make much
sense. Hide it when the abort condition is &amp;user-abort-error and skip directly
to the dump page.

* gnu/installer/steps.scm (&amp;user-abort-error): New variable.
(user-abort-error?): New procedure.
* gnu/installer/newt/final.scm (run-install-failed-page): Raise a
user-abort-error.
* gnu/installer/newt/welcome.scm (run-welcome-page): Ditto.
* gnu/installer.scm (installer-program): Hide the backtrace page and directly
propose to dump the report when the a &amp;user-abort-error is raised.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2022-08-08 11:54:25 +0200'>2022-08-08</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=ff9522fb69b9f4a31a5b766029e26dc53a2d1cf8'>installer: Add comments and vertical space to the generated config.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/parted.scm (user-partitions-&gt;configuration): Introduce
vertical space and a comment.
* gnu/installer/services.scm (G_): New macro.
(%system-services): Add comment for OpenSSH.
(system-services-&gt;configuration): Add vertical space and comments.
* gnu/installer/user.scm (users-&gt;configuration): Add comment.
* gnu/installer/steps.scm (format-configuration): Add comment.
(configuration-&gt;file): Expound leading comment.  Pass #:format-comment
to 'pretty-print-with-comments/splice'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-08-08 11:54:24 +0200'>2022-08-08</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=cd1a98b928be9602ebf103744164ace7bfcae22c'>installer: Render the final configuration with (guix read-print).</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer.scm (module-to-import?): Return #t for (guix read-print).
* gnu/installer/steps.scm (configuration-&gt;file): Use
'pretty-print-with-comments/splice' instead of 'for-each' and 'pretty-print'.
</span></span></td><td>Ludovic Courtès</td></tr>