[llvm] Fix compress/decompress in LLVM Offloading API (PR #150064)

[David Salinas via llvm-commits]

================
@@ -32,42 +32,56 @@ namespace llvm {
 
 namespace object {
 
+// CompressedOffloadBundle represents the format for the compressed offload
+// bundles.
+//
+// The format is as follows:
+// - Magic Number (4 bytes) - A constant "CCOB".
----------------
david-salinas wrote:

This is actually pulled from "clang/include/clang/Driver/OffloadBundler.h".  The intent here is to migrate the offloading API in clang/lib/Driver (used by the clang-offload-bundler) into this LLVM API.  In this case, I need to add (copy) this code from the Clang API, so that the llvm-* tools can decompress the offload bundles that the Clang Driver API created.  For now we would/will have this code duplicated, which is not ideal, until we can have the clang-offload-bundler use this LLVM API to handle compress/decompress.

https://github.com/llvm/llvm-project/pull/150064