replace MIN/MAX constants with min_value/max_value functions

MIN and MAX were breaking the build for me. min_value and max_value do not.

Author: matthew-piziak

src/test/run-fail/iter-step-overflow-debug.rs

@@ -14,13 +14,13 @@ use std::panic;
 
 fn main() {
     let r = panic::catch_unwind(|| {
-        let mut it = u8::MAX..;
+        let mut it = u8::max_value()..;
         it.next();
     });
     assert!(r.is_err());
 
     let r = panic::catch_unwind(|| {
-        let mut it = i8::MAX..;
+        let mut it = i8::max_value()..;
         it.next();
     });
     assert!(r.is_err());

src/test/run-fail/iter-step-overflow-ndebug.rs

@@ -11,9 +11,9 @@
 // compile-flags: -C debug_assertions=no
 
 fn main() {
-    let mut it = u8::MAX..;
-    assert_eq!(it.next(), u8::MIN);
+    let mut it = u8::max_value()..;
+    assert_eq!(it.next(), u8::min_value());
 
-    let mut it = i8::MAX..;
-    assert_eq!(it.next(), i8::MIN);
+    let mut it = i8::max_value()..;
+    assert_eq!(it.next(), i8::min_value());
 }