ELF: Make link() to take an output stream to which error messages are written.

http://reviews.llvm.org/D16668

llvm-svn: 259597
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 8340206..a417204 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -29,8 +29,9 @@
 Configuration *elf2::Config;
 LinkerDriver *elf2::Driver;
 
-bool elf2::link(ArrayRef<const char *> Args) {
+bool elf2::link(ArrayRef<const char *> Args, raw_ostream &Error) {
   HasError = false;
+  ErrorOS = &Error;
   Configuration C;
   LinkerDriver D;
   Config = &C;