Pascal: Fix code generated for minint

Pascal has a MAXINT constant, but seems to lack a corresponding
MININT so our generated Pascal code failed to compile.

We now use (-MAXINT - 1) for Snowball `minint`, which is correct
assuming two's complement representation.

compiler/generator_pascal.c

@@ -272,7 +272,7 @@ static void generate_AE(struct generator * g, struct node * p) {
         case c_maxint:
             write_string(g, "MAXINT"); break;
         case c_minint:
-            write_string(g, "MININT"); break;
+            write_string(g, "(-MAXINT - 1)"); break;
         case c_neg:
             write_char(g, '-'); generate_AE(g, p->right); break;
         case c_multiply: