package/pound: force libopenssl

Force libopenssl to avoid the following build failure with libressl
raised since bump to version 4.8 in commit
525cb6a8fbe04a959ea6e3a21a3f6f8828d7e9dc:

pound.c: In function 'main':
pound.c:971:27: error: 'l_id' undeclared (first use in this function)
  971 |   CRYPTO_set_id_callback (l_id);
      |                           ^~~~

Fixes:
 - http://autobuild.buildroot.org/results/692db714aa8b0dcfb67fd99977fb6f33c5d4810c

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 648502bdbdcf6a8996db897af731fd2219d777d1)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pound/Config.in

@@ -4,6 +4,7 @@ config BR2_PACKAGE_POUND
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_USE_MMU # fork()
 	select BR2_PACKAGE_OPENSSL
+	select BR2_PACKAGE_OPENSSL_FORCE_LIBOPENSSL
 	help
 	  The Pound program is a reverse proxy, load balancer and HTTPS
 	  front-end for Web server(s). Pound was developed to enable