MINOR: report the Lua version in -vv

As of the other libraries used by haproxy, it can be useful to display the Lua
version used at compilation time.
A new line is added to "haproxy -vv", which shows if Lua is supported by the
binary, and with which version it was compiled.
diff --git a/src/haproxy.c b/src/haproxy.c
index c3d6255..19687b2 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -334,6 +334,12 @@
 	printf("Built without PCRE support (using libc's regex instead)\n");
 #endif
 
+#ifdef USE_LUA
+	printf("Built with Lua version : %s\n", LUA_RELEASE);
+#else
+	printf("Built without Lua support\n");
+#endif
+
 #if defined(CONFIG_HAP_TRANSPARENT) || defined(CONFIG_HAP_CTTPROXY)
 	printf("Built with transparent proxy support using:"
 #if defined(CONFIG_HAP_CTTPROXY)