nut: fix build on macos

nut build fails on macos due to:
1. configure script can not use AR env var due to OpenWrt build
system provides only executable name (e.g. aarch64-openwrt-linux-musl-gcc-ar)
but configure script checks if AR has '/'. As a result, configure
script ignores AR env var and uses system `ar` but macos `ar` is
not compatible with the objects generated by OpenWrt GCC toolchain.

This commit explicitly sets ac_cv_path_AR=$(TARGET_AR) to use
OpenWrt toolchain AR.

2. configure script detects if build host is macos and adds
macosx_ups driver as a build target, but this driver can not be
build with OpenWrt toolchain because OpenWrt is Linux.

This commit explicitly disables macosx_ups driver using configure
flag --without-macosx_ups

Signed-off-by: Sergey V. Lobanov <sergey@lobanov.in>

net/nut/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=nut
 PKG_VERSION:=2.7.4
-PKG_RELEASE:=26
+PKG_RELEASE:=27
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=http://www.networkupstools.org/source/2.7/
@@ -524,6 +524,9 @@ $(eval $(call DriverDescription,usb,nutdrv_qx,\
 $(eval $(call DriverDescription,neon,netxml-ups,\
         Driver for NetXML based UPS equipment))
 
+CONFIGURE_VARS += \
+	ac_cv_path_AR=$(TARGET_AR)
+
 CONFIGURE_ARGS += \
 	--sysconfdir=/etc/nut \
 	--datadir=/usr/share/nut \
@@ -542,6 +545,7 @@ CONFIGURE_ARGS += \
 	--without-freeipmi \
 	--$(if $(CONFIG_NUT_SSL),with,without)-ssl $(if $(CONFIG_NUT_SSL),--with-openssl) \
 	--without-libltdl \
+	--without-macosx_ups \
 	--with-statepath=/var/run/nut \
 	--with-drvpath=/lib/nut \
 	--with-user=root \