Revert "Add support for computing SHA1 in LLVM"

This reverts commit r265096, r265095, and r265094.
Windows build is broken, and the validation does not pass.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265102
diff --git a/llvm/lib/IR/ModuleSummaryIndex.cpp b/llvm/lib/IR/ModuleSummaryIndex.cpp
index c23e072..16b58dd 100644
--- a/llvm/lib/IR/ModuleSummaryIndex.cpp
+++ b/llvm/lib/IR/ModuleSummaryIndex.cpp
@@ -37,11 +37,9 @@
 
     // Add the module path string ref for this module if we haven't already
     // saved a reference to it.
-    if (ModPath.empty()) {
-      auto Path = Info->summary()->modulePath();
-      ModPath = addModulePath(Path, NextModuleId, Other->getModuleHash(Path))
-                    ->first();
-    } else
+    if (ModPath.empty())
+      ModPath = addModulePath(Info->summary()->modulePath(), NextModuleId);
+    else
       assert(ModPath == Info->summary()->modulePath() &&
              "Each module in the combined map should have a unique ID");