radsecproxy: update to 1.8.1

Removed upstreamed OpenSSL patch.

Added PKG_BUILD_PARALLEL for faster compilation.

Cleaned up Makefile slightly.

Ran init script through shellcheck.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/radsecproxy/patches/200-logdest-on-foreground.patch

@@ -1,6 +1,6 @@
 --- a/radsecproxy.c
 +++ b/radsecproxy.c
-@@ -3385,15 +3385,13 @@ int radsecproxy_main(int argc, char **ar
+@@ -3005,15 +3005,13 @@ int radsecproxy_main(int argc, char **argv) {
  	options.loglevel = loglevel;
      else if (options.loglevel)
  	debug_set_level(options.loglevel);