dev-libs/libbson: fix building against >=sphinx-3

Closes: https://bugs.gentoo.org/716774
Package-Manager: Portage-2.3.99, Repoman-2.3.22
Signed-off-by: Thomas Deutschmann <whissi@gentoo.org>

dev-libs/libbson/files/libbson-1.16.2-sphinx.patch

@@ -0,0 +1,19 @@
+https://bugs.gentoo.org/716774
+
+--- a/build/sphinx/taglist.py
++++ b/build/sphinx/taglist.py
+@@ -24,7 +24,12 @@ THE SOFTWARE.
+ """
+ 
+ from docutils import nodes, utils
+-from sphinx.environment import NoUri
++
++try:
++    from sphinx.environment import NoUri
++except ImportError:
++    from sphinx.errors import NoUri
++
+ try:
+     from sphinx.util.compat import Directive
+ except ImportError:
+ 

dev-libs/libbson/libbson-1.16.2.ebuild

@@ -19,6 +19,7 @@ DEPEND="dev-python/sphinx"
 PATCHES=(
 	"${FILESDIR}/${PN}-1.14.0-no-docs.patch"
 	"${FILESDIR}/${PN}-1.16.2-single-doc-job.patch"
+	"${FILESDIR}/${PN}-1.16.2-sphinx.patch"
 )
 
 S="${WORKDIR}/mongo-c-driver-${PV}"