Update clients of path.rs to use new API.

In most cases this involved removing a ~str allocations or clones
(yay), or coercing a ~str to a slice.  In a few places, I had to bind
an intermediate Path (e.g. path.pop() return values), so that it would
live long enough to support the borrowed &str.

And in a few places, where the code was actively using the property
that the old API returned ~str's, I had to put in to_owned() or
clone(); but in those cases, we're trading an allocation within the
path.rs code for one in the client code, so they neutralize each
other.

src/compiletest/compiletest.rs

@@ -307,8 +307,9 @@ pub fn make_test_name(config: &config, testfile: &Path) -> test::TestName {
     // Try to elide redundant long paths
     fn shorten(path: &Path) -> ~str {
         let filename = path.filename();
-        let dir = path.pop().filename();
-        fmt!("%s/%s", dir.unwrap_or_default(~""), filename.unwrap_or_default(~""))
+        let p = path.pop();
+        let dir = p.filename();
+        fmt!("%s/%s", dir.unwrap_or_default(""), filename.unwrap_or_default(""))
     }
 
     test::DynTestName(fmt!("[%s] %s",

src/compiletest/runtest.rs

@@ -880,7 +880,7 @@ fn _arm_push_aux_shared_library(config: &config, testfile: &Path) {
     let dirs = os::list_dir_path(&Path(tstr));
     for file in dirs.iter() {
 
-        if (file.filetype() == Some(~".so")) {
+        if (file.filetype() == Some(".so")) {
 
             let copy_result = procsrv::run("", config.adb_path,
                 [~"push", file.to_str(), config.adb_test_dir.clone()],