Begin valgrinding some run-fail tests that unwind correctly

Issue #236

src/test/run-fail/explicit-fail-msg.rs

@@ -1,3 +1,2 @@
 // error-pattern:wooooo
-// no-valgrind
 fn main() { let a = 1; if 1 == 1 { a = 2; } fail "woooo" + "o"; }

src/test/run-fail/fmt-fail.rs

@@ -1,5 +1,4 @@
 // error-pattern:meh
-// no-valgrind
 use std;
 
 fn main() { let str_var: str = "meh"; fail #fmt["%s", str_var]; }

src/test/run-fail/linked-failure.rs

@@ -2,7 +2,6 @@
 
 // error-pattern:1 == 2
 // no-valgrind
-
 use std;
 import std::task;
 import std::comm::port;

src/test/run-fail/vec-overrun.rs

@@ -1,7 +1,6 @@
 // -*- rust -*-
 
 // error-pattern:bounds check
-// no-valgrind
 fn main() {
     let v: [int] = [10];
     let x: int = 0;

src/test/run-fail/vec-underrun.rs

@@ -1,7 +1,6 @@
 // -*- rust -*-
 
 // error-pattern:bounds check
-// no-valgrind
 fn main() {
     let v: [int] = [10, 20];
     let x: int = 0;