A couple of fixes from upstream's CVS-repository.
--- sys.c	2017-10-22 19:48:07.000000000 -0400
+++ sys.c	2023-07-21 18:36:30.000000000 -0400
@@ -1523,5 +1523,5 @@
 	info.name = name;
 	for (isubr = subrs_gra.len; 0 < isubr--;) {
-	  if (0==strcmp(((char **)subrs_gra.elts)[isubr], name)) {
+	  if (0==strcmp(((subr_info *)subrs_gra.elts)[isubr].name, name)) {
 	    scm_warn(s_redefining, (char *)name, UNDEFINED);
 	    goto foundit;
@@ -1650,5 +1650,6 @@
   estk = scm_estk;
 #else
-  from[1] = BOOL_F;		/* Can't write to parent stack */
+  /* Can't write to parent stack, it is now shared. */
+  SCM_ESTK_PARENT_WRITABLEP(scm_estk) = BOOL_F;
   estk = must_malloc_cell((long)n*sizeof(SCM),
 			  MAKE_LENGTH(n, tc7_vector), s_cont);
@@ -3166,5 +3188,5 @@
 	(heap_cells - cells_allocated <= scm_ecache_len) || IMP(freelist)) {
       alloc_some_heap();
-      growth_mon("number of heaps", (long)(hplim_ind/2), "segments", !0);
+      growth_mon(s_numheaps, (long)(hplim_ind/2), "segments", !0);
       growth_mon(s_heap, heap_cells, s_cells, !0);
     }