Remove unused imports.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>

src/libstd/io/net/addrinfo.rs

@@ -102,10 +102,6 @@ fn lookup(hostname: Option<&str>, servname: Option<&str>, hint: Option<Hint>)
 // permission without help of apk
 #[cfg(test, not(target_os = "android"))]
 mod test {
-    use io::net::ip::Ipv4Addr;
-    use prelude::*;
-    use super::*;
-
     iotest!(fn dns_smoke_test() {
         let ipaddrs = get_host_addresses("localhost").unwrap();
         let mut found_local = false;

src/libstd/num/f32.rs

@@ -907,7 +907,6 @@ mod tests {
 
     use num::*;
     use num;
-    use mem;
 
     #[test]
     fn test_num() {

src/libstd/num/f64.rs

@@ -909,7 +909,6 @@ mod tests {
 
     use num::*;
     use num;
-    use mem;
 
     #[test]
     fn test_num() {

src/libstd/num/int_macros.rs

@@ -444,7 +444,6 @@ mod tests {
     use num;
     use num::CheckedDiv;
     use num::Bitwise;
-    use mem;
 
     #[test]
     fn test_num() {

src/libstd/num/mod.rs

@@ -1087,7 +1087,6 @@ pub fn test_num<T:Num + NumCast>(ten: T, two: T) {
 mod tests {
     use prelude::*;
     use super::*;
-    use num;
     use i8;
     use i16;
     use i32;

src/libstd/num/uint_macros.rs

@@ -315,7 +315,6 @@ mod tests {
     use num;
     use num::CheckedDiv;
     use num::Bitwise;
-    use mem;
     use u16;
 
     #[test]