package/netsnmp: fix musl build

Fix the following musl build failure raised since bump to version 5.9.4
in commit 868603755c16296ae2a61845891edeafc36e48ca:

large_fd_set.c: In function 'LFD_SET':
../include/net-snmp/net-snmp-config.h:1614:30: error: unknown type name 'unknown'; did you mean 'union'?
 1614 | #define NETSNMP_FD_MASK_TYPE unknown
      |                              ^~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/394ebf93621c33dc2ddf370297268e6de9de7c9a

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit dad81003c905c5fe33599c1676ed46108b512bc0)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/netsnmp/0001-Fix-configuration-of-NETSNMP_FD_MASK_TYPE.patch

@@ -0,0 +1,38 @@
+From a62169f1fa358be8f330ea8519ade0610fac525b Mon Sep 17 00:00:00 2001
+From: Adam Gajda <adgajda@users.noreply.github.com>
+Date: Mon, 2 Oct 2023 16:40:31 +0200
+Subject: [PATCH] Fix configuration of NETSNMP_FD_MASK_TYPE
+
+Upstream: https://github.com/net-snmp/net-snmp/commit/a62169f1fa358be8f330ea8519ade0610fac525b
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+---
+ configure                        | 2 +-
+ configure.d/config_project_types | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/configure b/configure
+index 9f0a173d8a..945a27c663 100755
+--- a/configure
++++ b/configure
+@@ -30871,7 +30871,7 @@ CFLAGS="$CFLAGS -Werror"
+ 
+ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for the type of fd_set::fds_bits" >&5
+ printf %s "checking for the type of fd_set::fds_bits... " >&6; }
+-for type in __fd_mask __int32_t unknown; do
++for type in __fd_mask __int32_t long\ int unknown; do
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+ 
+diff --git a/configure.d/config_project_types b/configure.d/config_project_types
+index 1b4c66b95e..a78e8ebb06 100644
+--- a/configure.d/config_project_types
++++ b/configure.d/config_project_types
+@@ -66,7 +66,7 @@ netsnmp_save_CFLAGS=$CFLAGS
+ CFLAGS="$CFLAGS -Werror"
+ 
+ AC_MSG_CHECKING([for the type of fd_set::fds_bits])
+-for type in __fd_mask __int32_t unknown; do
++for type in __fd_mask __int32_t long\ int unknown; do
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
+ #include <sys/select.h>
+ #include <stddef.h>

package/netsnmp/netsnmp.mk

@@ -40,6 +40,8 @@ NETSNMP_INSTALL_STAGING_OPTS = DESTDIR=$(STAGING_DIR) LIB_LDCONFIG_CMD=true inst
 NETSNMP_INSTALL_TARGET_OPTS = DESTDIR=$(TARGET_DIR) LIB_LDCONFIG_CMD=true install
 NETSNMP_MAKE = $(MAKE1)
 NETSNMP_CONFIG_SCRIPTS = net-snmp-config
+# We're patching configure.d/config_project_types
+NETSNMP_AUTORECONF = YES
 
 ifeq ($(BR2_ENDIAN),"BIG")
 NETSNMP_CONF_OPTS += --with-endianness=big