Add a test for std._vec.init_elt, and an XFAILed test for std._vec.init_fn.

src/test/run-pass/vec-lib.rs

+use std;
+
+fn test_init_elt() {
+  let vec[uint] v = std._vec.init_elt[uint](uint(5), uint(3));
+  check (std._vec.len[uint](v) == uint(3));
+  check (v.(0) == uint(5));
+  check (v.(1) == uint(5));
+  check (v.(2) == uint(5));
+}
+
+fn id(uint x) -> uint {
+  ret x;
+}
+fn test_init_fn() {
+  let fn(uint)->uint op = id;
+  let vec[uint] v = std._vec.init_fn[uint](op, uint(5));
+  // FIXME #108: Can't call templated function twice in the same
+  // program, at the moment.
+  //check (std._vec.len[uint](v) == uint(5));
+  check (v.(0) == uint(0));
+  check (v.(1) == uint(1));
+  check (v.(2) == uint(2));
+  check (v.(3) == uint(3));
+  check (v.(4) == uint(4));
+}
+
+fn main() {
+  test_init_elt();
+  //XFAIL: test_init_fn();  // Segfaults.
+}
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