[clang] Remove a duplicate action kind table entry.

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

Differential Revision: https://reviews.llvm.org/D119826

Author: iains

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2406,7 +2406,6 @@ static const auto &getFrontendActionTable() {
       {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},