Fix pretty tests

Author: varkor

src/test/pretty/block-disambig.rs

@@ -7,7 +7,7 @@
 
 use std::cell::Cell;
 
-fn test1() { let val = &0; { } *val; }
+fn test1() { let val = &0; { } let _ = *val; }
 
 fn test2() -> isize { let val = &0; { } *val }
 

src/test/pretty/unary-op-disambig.rs

@@ -16,4 +16,4 @@ fn alt_semi() -> isize { match true { true => { f() } _ => { } }; -1 }
 
 fn alt_no_semi() -> isize { (match true { true => { 0 } _ => { 1 } }) - 1 }
 
-fn stmt() { { f() }; -1; }
+fn stmt() { { f() }; let _ = -1; }