Replaced the BUILTIN32_dlopen() ERR() by a WARN().

diff --git a/relay32/builtin32.c b/relay32/builtin32.c
index e91c52d..b437711 100644
--- a/relay32/builtin32.c
+++ b/relay32/builtin32.c
@@ -94,7 +94,7 @@
     strcat( buffer, ".so" );
 
     if (!(handle = ELFDLL_dlopen( buffer, RTLD_NOW )))
-        ERR( "failed to load %s: %s\n", buffer, dlerror() );
+        WARN( "failed to load %s: %s\n", buffer, dlerror() );
     return handle;
 #else
     return NULL;