libguile/coop-threads.c needs root.h for various definitions

[thi]

Index: coop-threads.c
===================================================================
RCS file: /cvs/guile/guile/guile-core/libguile/coop-threads.c,v
retrieving revision 1.17
diff -c -p -w -c -r1.17 coop-threads.c
*** coop-threads.c      2000/03/12 16:09:34     1.17
--- coop-threads.c      2000/03/19 13:55:58
***************
*** 46,51 ****
--- 46,52 ----
  
  #include "validate.h"
  #include "coop-threads.h"
+ #include "root.h"
  
  /* A counter of the current number of threads */
  size_t scm_thread_count = 0;