[ORC][examples] Export exectuable symbols explicitly in LLJITWithExecutorProcessControl

[sgraenitz]

Summary

Functions in static code that should be callable from JITed code must be exported. For dynamic libraries extern functions are exported by default. For exectuables, linkers usually strip them away unless we explicitly ask for keeping them.

[sgraenitz]

Issue reported during review D110260. With this fix, nm should return something like this now:

➜ nm bin/LLJITWithExecutorProcessControl | grep return1
0000000100004c10 T _return1

[xgupta]

Yes it is correctly return that symbol, LGTM.

[sgraenitz]

FYI Included one more typo fix in ExecutorAddress.h (Edit: This was in the other review.)

llvm/examples/OrcV2Examples/LLJITWithExecutorProcessControl/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Core
   ExecutionEngine
   IRReader
   OrcJIT
   Support
   nativecodegen
   )
 
 add_llvm_example(LLJITWithExecutorProcessControl
   LLJITWithExecutorProcessControl.cpp
   )
+
+export_executable_symbols(LLJITWithExecutorProcessControl)