Use UINT_MAX instead of -1 to set unsigned to maximum value.

The Sun C compiler warns when -1 is used to initialize an unsigned.
(cherry picked from commit 7d588d699b)

vpi/sys_scanf.c

@@ -28,6 +28,7 @@
 # include  <stdio.h>
 # include  <stdlib.h>
 # include  <math.h>
+# include  <limits.h>
 # include  <assert.h>
 
 /*
@@ -802,7 +803,7 @@ static int scan_format(vpiHandle callh, struct byte_source*src, vpiHandle argv,
 		     * parse it generically first. */
 
 		  unsigned suppress_flag = 0;
-		  unsigned max_width = -1;
+		  unsigned max_width = UINT_MAX;
 		  int code = 0;
 
 		    /* Look for the suppression character '*'. */