Accommodate the "int literal is too large" error message currently embedded in rustc.

Author: pnkfelix

src/test/compile-fail/int-literal-too-large-span.rs

@@ -11,7 +11,7 @@
 // issue #17123
 
 fn main() {
-    100000000000000000000000000000000 //~ ERROR isize literal is too large
+    100000000000000000000000000000000is //~ ERROR int literal is too large
 
         ; // the span shouldn't point to this.
 }

src/test/compile-fail/issue-5544-b.rs

@@ -9,6 +9,6 @@
 // except according to those terms.
 
 fn main() {
-    let _i = 0xff_ffff_ffff_ffff_ffff;
-    //~^ ERROR isize literal is too large
+    let _i = 0xff_ffff_ffff_ffff_ffff_is;
+    //~^ ERROR int literal is too large
 }