Add the --chroot option for --reproduce.

Summary:
If the linker is invoked with `--chroot /foo` and `/bar/baz.o`, it
tries to read the file from `/foo/bar/baz.o`. This feature is useful
when you are dealing with files created by the --reproduce option.

Reviewers: grimar

Subscribers: llvm-commits, emaste

Differential Revision: https://reviews.llvm.org/D35517

llvm-svn: 308646

lld/ELF/ScriptParser.cpp

@@ -256,7 +256,7 @@ void ScriptParser::addFile(StringRef S) {
     }
   }
 
-  if (sys::path::is_absolute(S)) {
+  if (S.startswith("/")) {
     Driver->addFile(S, /*WithLOption=*/false);
   } else if (S.startswith("=")) {
     if (Config->Sysroot.empty())