unbound: fix build on non-linux systems

Override places that call uname to detect target features

Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry picked from commit cc1d0aa3d2)

net/unbound/Makefile

@@ -158,6 +158,8 @@ define Package/libunbound/config
 	endif
 endef
 
+CONFIGURE_VARS += UNAME=Linux
+
 CONFIGURE_ARGS += \
 	--disable-dsa \
 	--disable-gost \

net/unbound/patches/010-configure_uname.patch

@@ -0,0 +1,20 @@
+--- a/configure.ac
++++ b/configure.ac
+@@ -765,7 +765,7 @@ if test x_$ub_test_python != x_no; then
+    fi
+ fi
+ 
+-if test "`uname`" = "NetBSD"; then
++if test "${UNAME:-`uname`}" = "NetBSD"; then
+ 	NETBSD_LINTFLAGS='"-D__RENAME(x)=" -D_NETINET_IN_H_'
+ 	AC_SUBST(NETBSD_LINTFLAGS)
+ fi
+@@ -1210,7 +1210,7 @@ esac
+ AC_ARG_ENABLE(tfo-client, AS_HELP_STRING([--enable-tfo-client],[Enable TCP Fast Open for client mode]))
+ case "$enable_tfo_client" in
+ 	yes)
+-		case `uname` in
++		case ${UNAME:-`uname`} in
+ 			Linux) AC_CHECK_DECL([MSG_FASTOPEN], [AC_MSG_WARN([Check the platform specific TFO kernel parameters are correctly configured to support client mode TFO])],
+ 			                     [AC_MSG_ERROR([TCP Fast Open is not available for client mode: please rerun without --enable-tfo-client])], 
+ 			                     [AC_INCLUDES_DEFAULT