Perform more C warning fixup on all C source files and headers.

winsup/testsuite/winsup.api/ltp/dup03.c

@@ -110,14 +110,13 @@
 #include <errno.h>
 #include <string.h>
 #include <signal.h>
-#include <stdlib.h>
 #include "test.h"
 #include "usctest.h"
 
 void setup();
-void cleanup();
+void cleanup(void) __attribute__((noreturn));
 
-char *TCID="dup03"; 		/* Test program identifier.    */
+const char *TCID="dup03"; 		/* Test program identifier.    */
 int TST_TOTAL=1;    		/* Total number of test cases. */
 extern int Tst_count;		/* Test Case counter for tst_* routines */