package/libdnet: replace PKG_PYTHON_DISTUTILS_ENV

Replace PKG_PYTHON_DISTUTILS_ENV by PKG_PYTHON_SETUPTOOLS_ENV as libdnet
uses setuptools instead of distutils since version 1.16.2 and
https://github.com/ofalk/libdnet/commit/4e4fc687953105b66bcc847a68869126ac3ec918

This will avoid the following build failure raised since commit
09de823cbc7bd50a40e25f4166b4e42be94b0c7b:

In file included from /home/fabrice/buildroot/output/per-package/libdnet/host/include/python3.12/Python.h:38,
                 from ./dnet.c:40:
/home/fabrice/buildroot/output/per-package/libdnet/host/include/python3.12/pyport.h:586:2: error: #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)."
  586 | #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)."
      |  ^~~~~

Fixes: 09de823cbc7bd50a40e25f4166b4e42be94b0c7b
(No autobuilder failure (yet))

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 9dfaa179dbc6efba3f2033e35ef9c3b2653061b8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libdnet/libdnet.mk

@@ -19,7 +19,7 @@ LIBDNET_DEPENDENCIES = host-pkgconf
 ifeq ($(BR2_PACKAGE_LIBDNET_PYTHON),y)
 LIBDNET_DEPENDENCIES += libbsd host-python-cython python3
 LIBDNET_CONF_OPTS += --with-python=$(HOST_DIR)/bin
-LIBDNET_MAKE_ENV += $(PKG_PYTHON_DISTUTILS_ENV)
+LIBDNET_MAKE_ENV += $(PKG_PYTHON_SETUPTOOLS_ENV)
 LIBDNET_INSTALL_TARGET_OPTS = $(LIBDNET_MAKE_OPTS) DESTDIR=$(TARGET_DIR) INSTALL_STRIP_FLAG=-s install-exec
 LIBDNET_INSTALL_STAGING_OPTS = $(LIBDNET_MAKE_OPTS) DESTDIR=$(STAGING_DIR) install
 endif