[llvm] [Offload] Add an `unloadBinary` interface to PluginInterface (PR #143873)

[Ross Brunton via llvm-commits]

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@@ -13,7 +13,9 @@
 def : Function {
     let name = "olCreateProgram";
     let desc = "Create a program for the device from the binary image pointed to by `ProgData`.";
-    let details = [];
+    let details = [
+        "`ProgData` must remain valid for the entire lifetime of the output `Program` handle",
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RossBrunton wrote:

It also looks like program handles already make a copy (which lives as long as the program handle itself), which I assumed they didn't.

https://github.com/llvm/llvm-project/pull/143873