appending zero bytes to an empty array failed it

CHANGES

@@ -17,6 +17,7 @@
   add support for Solaris /dev/poll
   add lose32 support (broken, please don't use!)
   head -1 -> head -n 1
+  apending 0 bytes to an empty array would fail it
 
 0.16:
   add buffer_fromsa (make buffer from stralloc)

array/array_catb.c

@@ -3,6 +3,7 @@
 
 void array_catb(array* to,const char* from,uint64 len) {
   long l;
+  if (!len) return;
   if (to->allocated<0) return;
   if (to->initialized+len<to->initialized) {
 fail: