indent(1): Bail out if there's no more space on the parser stack.

Also increase the stack size still keeping a conservative value of 256.
This is based on a similar changes done for PostgreSQL which instead
uses a stack size of 1000.

Differential Revision: https://reviews.freebsd.org/D6966  (Partial)
Submitted by:	Piotr Stefaniak (with changes)

usr.bin/indent/indent_globs.h

@@ -226,7 +226,7 @@ struct fstate
             bodyf;		/* major body font */
 
 
-#define STACKSIZE 150
+#define	STACKSIZE 256
 
 struct parser_state {
     int         last_token;

usr.bin/indent/parse.c

@@ -42,6 +42,7 @@ static char sccsid[] = "@(#)parse.c	8.1 (Berkeley) 6/6/93";
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <err.h>
 #include <stdio.h>
 #include "indent_globs.h"
 #include "indent_codes.h"
@@ -200,6 +201,9 @@ parse(int tk) /* tk: the code for the construct scanned */
 
     }				/* end of switch */
 
+    if (ps.tos >= STACKSIZE)
+	errx(1, "Parser stack overflow");
+
     reduce();			/* see if any reduction can be done */
 
 #ifdef debug