From: Richard Purdie <richard.purdie@linuxfoundation.org>
Subject: [PATCH 06/12] libtool.m4: Handle "/" as a sysroot correctly

Update libtool.m4 to resolve a problem with lt_sysroot not being properly
updated if the option '--with[-libtool]-sysroot' is not provided when
running the 'configure' script for a package so that "/" as a sysroot
is handled correctly by libtool.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Upstream Report:
http://lists.gnu.org/archive/html/bug-libtool/2013-09/msg00005.html

Upstream-Status: Submitted [https://lists.gnu.org/archive/html/libtool-patches/2021-10/msg00018.html]

---
diff --git a/m4/libtool.m4 b/m4/libtool.m4
--- a/m4/libtool.m4
+++ b/m4/libtool.m4
@@ -1225,16 +1225,21 @@ dnl lt_sysroot will always be passed unquoted.  We quote it here
 dnl in case the user passed a directory name.
 lt_sysroot=
 case $with_libtool_sysroot in #(
- yes)
+ no)
    if test yes = "$GCC"; then
      lt_sysroot=`$CC --print-sysroot 2>/dev/null`
+     # Treat "/" the same a an unset sysroot. It seems to be more
+     # compatible across host platforms that way!?
+     if test "$lt_sysroot" = /; then
+       lt_sysroot=
+     fi
    fi
    ;; #(
+ yes|''|/)
+   ;; #(
  /*)
    lt_sysroot=`echo "$with_libtool_sysroot" | sed -e "$sed_quote_subst"`
    ;; #(
- no|'')
-   ;; #(
  *)
    AC_MSG_RESULT([$with_libtool_sysroot])
    AC_MSG_ERROR([The sysroot must be an absolute path.])