More test cases for classes with dtors

Tests that classes with dtors and multiple fields work correctly.
Closes #2708

Author: catamorphism

src/test/run-pass/issue-2708.rs

@@ -0,0 +1,17 @@
+class Font {
+    let fontbuf: uint;
+    let cairo_font: uint;
+    let font_dtor: uint;
+
+    new() {
+        self.fontbuf = 0;
+        self.cairo_font = 0;
+        self.font_dtor = 0;
+    }
+
+    drop { }
+}
+
+fn main() {
+    let _f = @Font();
+}

src/test/run-pass/resource-cycle3.rs

@@ -0,0 +1,50 @@
+// same as resource-cycle2, but be sure to give r multiple fields... 
+
+// Don't leak the unique pointers
+
+type u = {
+    a: int,
+    b: int,
+    c: *int
+};
+
+class r {
+  let v: u;
+  let w: int;
+  let x: *int;
+  new(v: u, w: int, _x: *int) unsafe { self.v = v; self.w = w; 
+    self.x = unsafe::reinterpret_cast(0);
+    /* self.x = x; */ }
+  drop unsafe {
+    let _v2: ~int = unsafe::reinterpret_cast(self.v.c);
+    // let _v3: ~int = unsafe::reinterpret_cast(self.x);
+  }
+}
+
+enum t = {
+    mut next: option<@t>,
+    r: r
+};
+
+fn main() unsafe {
+    let i1 = ~0xA;
+    let i1p = unsafe::reinterpret_cast(i1);
+    unsafe::forget(i1);
+    let i2 = ~0xA;
+    let i2p = unsafe::reinterpret_cast(i2);
+    unsafe::forget(i2);
+
+    let u1 = {a: 0xB, b: 0xC, c: i1p};
+    let u2 = {a: 0xB, b: 0xC, c: i2p};
+
+    let x1 = @t({
+        mut next: none,
+        r: r(u1, 42, i1p)
+    });
+    let x2 = @t({
+        mut next: none,
+        r: r(u2, 42, i2p)
+    });
+    x1.next = some(x2);
+    x2.next = some(x1);
+}