Modernize raw_fd_ostream's constructor a bit.

Take a StringRef instead of a "const char *".
Take a "std::error_code &" instead of a "std::string &" for error.

A create static method would be even better, but this patch is already a bit too
big.

llvm-svn: 216393
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index 7bf66e0..22bf35d9 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -535,8 +535,8 @@
                                                                      ++i) {
     SmallString<128> file_pathname(TestDirectory);
     path::append(file_pathname, i->filename);
-    std::string ErrMsg;
-    raw_fd_ostream file(file_pathname.c_str(), ErrMsg, sys::fs::F_None);
+    std::error_code EC;
+    raw_fd_ostream file(file_pathname, EC, sys::fs::F_None);
     ASSERT_FALSE(file.has_error());
     StringRef magic(i->magic_str, i->magic_str_len);
     file << magic;
@@ -553,23 +553,23 @@
   path::append(FilePathname, "test");
 
   {
-    raw_fd_ostream File(FilePathname.c_str(), ErrMsg, sys::fs::F_Text);
+    raw_fd_ostream File(FilePathname, ErrMsg, sys::fs::F_Text);
     EXPECT_EQ(ErrMsg, "");
     File << '\n';
   }
   {
-    auto Buf = MemoryBuffer::getFile(FilePathname.c_str());
+    auto Buf = MemoryBuffer::getFile(FilePathname);
     EXPECT_TRUE((bool)Buf);
     EXPECT_EQ(Buf.get()->getBuffer(), "\r\n");
   }
 
   {
-    raw_fd_ostream File(FilePathname.c_str(), ErrMsg, sys::fs::F_None);
+    raw_fd_ostream File(FilePathname, ErrMsg, sys::fs::F_None);
     EXPECT_EQ(ErrMsg, "");
     File << '\n';
   }
   {
-    auto Buf = MemoryBuffer::getFile(FilePathname.c_str());
+    auto Buf = MemoryBuffer::getFile(FilePathname);
     EXPECT_TRUE((bool)Buf);
     EXPECT_EQ(Buf.get()->getBuffer(), "\n");
   }