[llvm] [Offload] Implement 'olIsValidBinary' in offload and clean up (PR #159658)

[Ross Brunton via llvm-commits]

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@@ -24,6 +24,18 @@ def olCreateProgram : Function {
     let returns = [];
 }
 
+def olIsValidBinary : Function {
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RossBrunton wrote:

I'd prefer `olIsCompatibleBinary`; an ELF file (for example) can be a perfectly valid file yet not be compatible with the device.

https://github.com/llvm/llvm-project/pull/159658