Cleanup the interface for creating soft or hard links.

Before this patch the unix code for creating hardlinks was unused. The code
for creating symbolic links was implemented in lib/Support/LockFileManager.cpp
and the code for creating hard links in lib/Support/*/Path.inc.

The only use we have for these is in LockFileManager.cpp and it can use both
soft and hard links. Just have a create_link function that creates one or the
other depending on the platform.

llvm-svn: 203596
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index d5bee7a..91e421d 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -299,7 +299,7 @@
 
   // Two paths representing the same file on disk should still provide the
   // same unique id.  We can test this by making a hard link.
-  ASSERT_NO_ERROR(fs::create_hard_link(Twine(TempPath), Twine(TempPath2)));
+  ASSERT_NO_ERROR(fs::create_link(Twine(TempPath), Twine(TempPath2)));
   fs::UniqueID D2;
   ASSERT_NO_ERROR(fs::getUniqueID(Twine(TempPath2), D2));
   ASSERT_EQ(D2, F1);
@@ -365,7 +365,7 @@
   ASSERT_FALSE(TempPath3.endswith("."));
 
   // Create a hard link to Temp1.
-  ASSERT_NO_ERROR(fs::create_hard_link(Twine(TempPath), Twine(TempPath2)));
+  ASSERT_NO_ERROR(fs::create_link(Twine(TempPath), Twine(TempPath2)));
   bool equal;
   ASSERT_NO_ERROR(fs::equivalent(Twine(TempPath), Twine(TempPath2), equal));
   EXPECT_TRUE(equal);