Fix naming of libc that was mangled by recent module changes

It doesn't appear that rustc makes use of these strings so it didn't actually
break anything yet.

Author: brson

src/comp/driver/rustc.rs

@@ -35,11 +35,11 @@ fn default_environment(session::session sess,
                        str argv0,
                        str input) -> eval::env {
 
-    auto libc = "libc::so";
+    auto libc = "libc.so";
     alt (sess.get_targ_cfg().os) {
         case (session::os_win32) { libc = "msvcrt.dll"; }
-        case (session::os_macos) { libc = "libc::dylib"; }
-        case (session::os_linux) { libc = "libc::so.6"; }
+        case (session::os_macos) { libc = "libc.dylib"; }
+        case (session::os_linux) { libc = "libc.so.6"; }
     }
 
     ret

src/lib/linux_os.rs

@@ -4,7 +4,7 @@ import _vec::vbuf;
 // FIXME Somehow merge stuff duplicated here and macosx_os.rs. Made difficult
 // by https://github.com/graydon/rust/issues#issue/268
 
-native mod libc = "libc::so.6" {
+native mod libc = "libc.so.6" {
 
     fn open(sbuf s, int flags, uint mode) -> int;
     fn read(int fd, vbuf buf, uint count) -> int;

src/lib/macos_os.rs

@@ -1,7 +1,7 @@
 import _str::sbuf;
 import _vec::vbuf;
 
-native mod libc = "libc::dylib" {
+native mod libc = "libc.dylib" {
 
     fn open(sbuf s, int flags, uint mode) -> int;
     fn read(int fd, vbuf buf, uint count) -> int;