[clang] Remove a duplicate action kind table entry.

[iains]

Summary

We have two entries for OPT_emit_codegen_only in the frontend action kind
table, delete one.

[iains]

probably trivial - but, in case there's some subtlety I missed...

[jansvoboda11]

LGTM, must've been a mistake. Thanks!

clang/lib/Frontend/CompilerInvocation.cpp

static const std::pair<frontend::ActionKind, unsigned> Table[] = {
       {frontend::DumpRawTokens, OPT_dump_raw_tokens},
       {frontend::DumpTokens, OPT_dump_tokens},
       {frontend::EmitAssembly, OPT_S},
       {frontend::EmitBC, OPT_emit_llvm_bc},
       {frontend::EmitHTML, OPT_emit_html},
       {frontend::EmitLLVM, OPT_emit_llvm},
       {frontend::EmitLLVMOnly, OPT_emit_llvm_only},
       {frontend::EmitCodeGenOnly, OPT_emit_codegen_only},
-      {frontend::EmitCodeGenOnly, OPT_emit_codegen_only},
       {frontend::EmitObj, OPT_emit_obj},
       {frontend::ExtractAPI, OPT_extract_api},
 
       {frontend::FixIt, OPT_fixit_EQ},
       {frontend::FixIt, OPT_fixit},
 
       {frontend::GenerateModule, OPT_emit_module},
       {frontend::GenerateModuleInterface, OPT_emit_module_interface},