gtk-doc: don't use docdir set in environment in gtkdocize

The gtkdocize script was accidentally respecting $docdir from the
environment as the default documentation directory. This is a problem as
bitbake.conf exports $docdir, resulting in configure failures.

(From OE-Core rev: d7f8f56e2a91abbadf53fd4c48d6f0e55ac749d1)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-gnome/gtk-doc/files/0001-Don-t-use-docdir-from-environment.patch

@@ -0,0 +1,24 @@
+From 72dfeec0e49478b0bfb471c4155044391bad8e6c Mon Sep 17 00:00:00 2001
+From: Ross Burton <ross.burton@arm.com>
+Date: Fri, 8 Dec 2023 10:35:25 +0000
+Subject: [PATCH] Don't use docdir from environment
+
+Upstream-Status: Submitted [https://gitlab.gnome.org/GNOME/gtk-doc/-/merge_requests/73]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ buildsystems/autotools/gtkdocize.in | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/buildsystems/autotools/gtkdocize.in b/buildsystems/autotools/gtkdocize.in
+index 83127bf..76dcbfd 100755
+--- a/buildsystems/autotools/gtkdocize.in
++++ b/buildsystems/autotools/gtkdocize.in
+@@ -39,7 +39,7 @@ set - $args
+ 
+ # assume working directory if srcdir is not set
+ test "$srcdir" || srcdir=.
+-test "$docdir" || docdir="$srcdir"
++docdir="$srcdir"
+ 
+ # detect configure script
+ no_configure_found=0

meta/recipes-gnome/gtk-doc/gtk-doc_1.33.2.bb

@@ -26,6 +26,7 @@ SRC_URI += "file://0001-Do-not-hardocode-paths-to-perl-python-in-scripts.patch \
            file://0001-Do-not-error-out-if-xsltproc-is-not-found.patch \
            file://conditionaltests.patch \
            file://no-clobber.patch \
+           file://0001-Don-t-use-docdir-from-environment.patch \
            "
 SRC_URI:append:class-native = " file://pkg-config-native.patch"