Add some missing #includes.

--- motif-2.3.8/demos/unsupported/xmform/xmform.c	2016-03-16 02:10:08.000000000 +0000
+++ motif-2.3.8/demos/unsupported/xmform/xmform.c	2025-07-04 03:33:35.807396821 +0100
@@ -55,6 +55,8 @@
 #include <Xm/PushB.h>
 #include <Xm/ArrowB.h>
 
+#include <stdlib.h>
+
 static void FillItPlease();
 static void NearlyEvenSpread();
 static Widget AddStem() ;
--- motif-2.3.8/lib/Xm/XpmI.h	2017-08-17 01:38:43.000000000 +0100
+++ motif-2.3.8/lib/Xm/XpmI.h	2025-07-04 03:32:16.628359013 +0100
@@ -122,6 +122,7 @@
 #include <sys/types.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <limits.h>
 #include <X11/Xmd.h>
 /* stdio.h doesn't declare popen on a Sequent DYNIX OS */