Fix some non-FFI-safe types in externs

Author: Keegan McAllister

src/liblibc/lib.rs

@@ -4542,7 +4542,7 @@ pub mod funcs {
                 pub fn glob(pattern: *const c_char,
                             flags: c_int,
                             errfunc: ::Nullable<extern "C" fn(epath: *const c_char,
-                                                              errno: c_int) -> int>,
+                                                              errno: c_int) -> c_int>,
                             pglob: *mut glob_t);
                 pub fn globfree(pglob: *mut glob_t);
             }

src/libtime/lib.rs

@@ -229,6 +229,8 @@ pub fn tzset() {
 
 /// Holds a calendar date and time broken down into its components (year, month, day, and so on),
 /// also called a broken-down time value.
+// FIXME: use c_int instead of i32?
+#[repr(C)]
 #[deriving(Clone, PartialEq, Eq, Show)]
 pub struct Tm {
     /// Seconds after the minute - [0, 60]