frr: rebuild for Python 3.9

srcpkgs/frr/template

@@ -1,7 +1,7 @@
 # Template file for 'frr'
 pkgname=frr
 version=7.4
-revision=1
+revision=2
 wrksrc="${pkgname}-${pkgname}-${version}"
 build_style=gnu-configure
 # chroot-texinfo is not able to build frr's docs
@@ -41,6 +41,11 @@ else
 	subpackages+=" frr-devel"
 fi
 
+post_patch() {
+	# Typo in configure macro
+	vsed -i m4/ax_python.m4 -e 's/"{py_ver}"/"${py_ver}"/g'
+}
+
 pre_configure() {
 	autoreconf -fi
 }