Fix casts of ptrace's third argument

* strace.c (maybe_allocate_tcb): Replace "(char *) 0" with NULL
as ptrace's third argument.
* linux/sparc64/get_scno.c (arch_get_scno): Cast third argument
of ptrace to "void *'.
* syscall.c (get_regs): Likewise.
* upeek.c (upeek): Likewise.
* util.c (umoven): Likewise.
diff --git a/util.c b/util.c
index e926f93..3979cab 100644
--- a/util.c
+++ b/util.c
@@ -1073,7 +1073,7 @@
 		n = addr & (sizeof(long) - 1);	/* residue */
 		addr &= -sizeof(long);		/* aligned address */
 		errno = 0;
-		u.val = ptrace(PTRACE_PEEKDATA, pid, (char *) addr, 0);
+		u.val = ptrace(PTRACE_PEEKDATA, pid, (void *) addr, 0);
 		switch (errno) {
 			case 0:
 				break;
@@ -1098,7 +1098,7 @@
 	}
 	while (len) {
 		errno = 0;
-		u.val = ptrace(PTRACE_PEEKDATA, pid, (char *) addr, 0);
+		u.val = ptrace(PTRACE_PEEKDATA, pid, (void *) addr, 0);
 		switch (errno) {
 			case 0:
 				break;
@@ -1241,7 +1241,7 @@
 		n = addr & (sizeof(long) - 1);	/* residue */
 		addr &= -sizeof(long);		/* aligned address */
 		errno = 0;
-		u.val = ptrace(PTRACE_PEEKDATA, pid, (char *)addr, 0);
+		u.val = ptrace(PTRACE_PEEKDATA, pid, (void *) addr, 0);
 		switch (errno) {
 			case 0:
 				break;
@@ -1270,7 +1270,7 @@
 
 	while (len) {
 		errno = 0;
-		u.val = ptrace(PTRACE_PEEKDATA, pid, (char *)addr, 0);
+		u.val = ptrace(PTRACE_PEEKDATA, pid, (void *) addr, 0);
 		switch (errno) {
 			case 0:
 				break;