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

winsup/testsuite/winsup.api/ltp/signal03.c

@@ -161,17 +161,15 @@
 
 #include <signal.h>
 #include <errno.h>  
-#include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
-#include <stdlib.h>
 #include <sys/wait.h>
 
 #include "test.h"
 #include "usctest.h"
 
 void setup();
-void cleanup();
+void cleanup(void) __attribute__((noreturn));
 void do_test();
 void sigdfl_test();
 void update_timings();
@@ -212,7 +210,7 @@ struct ipc_t {
     struct tblock timings;
 } Ipc_info;
 
-char *TCID = "signal03";
+const char *TCID = "signal03";
 int TST_TOTAL = 5;
 extern int Tst_count;           /* count of test items completed */