Include stdlib.h for exit(3).
Fix conflicting type for malloc(3).
Avoid casting pointers from/to int.

--- teco-orig/te_defs.h
+++ teco/te_defs.h
@@ -6,6 +6,7 @@
 /* version for multiple buffers 04/19/89 11.25                              */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <ctype.h>
 #include <setjmp.h>
 
--- teco-orig/te_rdcmd.c
+++ teco/te_rdcmd.c
@@ -94,7 +94,8 @@
 			qreg[i].f = cbuf.f;         /* put the old command string in its place */
 			if (qreg[i].f) qreg[i].f->b = (struct buffcell *) &qreg[i];
 			qreg[i].z = cbuf.z;
-			cbuf.f = (struct buffcell *) (cbuf.z = 0);      /* no old command string */
+			cbuf.f = NULL;              /* no old command string */
+			cbuf.z = 0;
 			err = 0;                    /* no previous error */
 			goto restart;
 			}
--- teco-orig/te_utils.c
+++ teco/te_utils.c
@@ -13,7 +13,6 @@
 
 struct buffcell *get_bcell()
     {
-    char *malloc();
     struct buffcell *p;
     int i;
 
--- teco-orig/te_window.c
+++ teco/te_window.c
@@ -1051,7 +1051,7 @@
 	pp->c = loc % CELLSIZE;
 	pp->dot = loc;
 	}
-    return( (int) pb0->f);
+    return(pb0->f != NULL);
     }
 
 /* routine to move N lines (back, forward, or 0)                */