Revert "Fix the libbcc SHA1 checksum dependency"

This reverts commit 89175b9e4c07df1302374421096d6e1355954ace.
diff --git a/lib/ExecutionEngine/CacheReader.cpp b/lib/ExecutionEngine/CacheReader.cpp
index 136cccd..408b1f7 100644
--- a/lib/ExecutionEngine/CacheReader.cpp
+++ b/lib/ExecutionEngine/CacheReader.cpp
@@ -148,6 +148,14 @@
          OBCC_VERSION, mpHeader->version);
     return false;
   }
+
+  if (memcmp(mpHeader->libbcc_build_checksum, libbcc_build_checksum, 41) != 0) {
+    mpHeader->libbcc_build_checksum[41 - 1] = '\0'; // ensure terminated
+    LOGW("Build checksum mismatch: lib %s cached %s\n", libbcc_build_checksum,
+         mpHeader->libbcc_build_checksum);
+    return false;
+  }
+
   return true;
 }