Adds support to collection using memcache.

This is the initial support to collections using memcache.

nginx/modsecurity/config.in

@@ -4,6 +4,7 @@ CFLAGS="$CFLAGS \
     @APR_CFLAGS@ \
     @APU_CFLAGS@ \
     @APXS_CFLAGS@ \
+    @LIBMEMCACHED_CFLAGS@ \
     @LIBXML2_CFLAGS@ \
     @LUA_CFLAGS@ \
     @MODSEC_EXTRA_CFLAGS@ \
@@ -17,6 +18,7 @@ CORE_LIBS="$CORE_LIBS \
     @APU_LINKLD@ \
     @APXS_CFLAGS@ \
     @CURL_LDADD@ \
+    @LIBMEMCACHED_LDADD@ \
     @LIBXML2_LDADD@ \
     @LUA_LDADD@ \
     @PCRE_LDADD@ \