Implement split_maybe_lib_args() to handle paths with spaces

When using `link_deps()` full paths are added to target_rustcflags,
which doesn't work well with split_maybe_args(), as it splits on space.

Fixes #81

src/runtest.rs

@@ -347,7 +347,7 @@ impl<'test> TestCx<'test> {
             .args(&["--unpretty", &pretty_type])
             .args(&["--target", &self.config.target])
             .arg("-L").arg(&aux_dir)
-            .args(self.split_maybe_args(&self.config.target_rustcflags))
+            .args(self.split_maybe_lib_args(&self.config.target_rustcflags))
             .args(&self.props.compile_flags)
             .envs(self.props.exec_env.clone());
 
@@ -403,7 +403,7 @@ actual:\n\
             rustc.args(&["--cfg", revision]);
         }
 
-        rustc.args(self.split_maybe_args(&self.config.target_rustcflags));
+        rustc.args(self.split_maybe_lib_args(&self.config.target_rustcflags));
         rustc.args(&self.props.compile_flags);
 
         self.compose_and_run_compiler(rustc, Some(src))
@@ -1448,7 +1448,7 @@ actual:\n\
         if self.props.force_host {
             rustc.args(self.split_maybe_args(&self.config.host_rustcflags));
         } else {
-            rustc.args(self.split_maybe_args(&self.config.target_rustcflags));
+            rustc.args(self.split_maybe_lib_args(&self.config.target_rustcflags));
         }
 
         rustc.args(&self.props.compile_flags);
@@ -1524,6 +1524,25 @@ actual:\n\
         }
     }
 
+    // Split library arguments on "-L" to handle paths with spaces properly. Like
+    // split_maybe_args(), empty strings filtered out.
+    fn split_maybe_lib_args(&self, argstr: &Option<String>) -> Vec<String> {
+        if let Some(ref s) = *argstr {
+            s.split("-L")
+                .filter_map(|p| {
+                    let p = p.trim();
+                    if p.is_empty() { None } else { Some(p.to_owned()) }
+                })
+                .fold(Vec::new(), |mut v, arg| {
+                    v.push("-L".to_owned());
+                    v.push(arg);
+                    v
+                })
+        } else {
+            Vec::new()
+        }
+    }
+
     fn make_cmdline(&self, command: &Command, libpath: &str) -> String {
         use util;