[flang] Avoid calling the linker when "-c" option is used

[PeteSteinfeld]

Summary

The title says it all.

[sscalpone]

Thanks Pete!

[PeteSteinfeld]

The file I modified no longer exists in the llvm-project source in the main branch.

flang/tools/f18/f18.cpp

if (arg.empty()) {
         arg == "-?") {
       llvm::errs()
           << "f18: LLVM Fortran compiler\n"
           << "\n"
           << "Usage: f18 [options] <input files>\n"
           << "\n"
           << "Defaults:\n"
           << "  When invoked with input files, and no options to tell\n"
-          << "  it otherwise, f18 will unparse its input and pass that on to an\n"
+          << "  it otherwise, f18 will unparse its input and pass that on to "
+             "an\n"
           << "  external compiler to continue the compilation.\n"
           << "  The external compiler is specified by the F18_FC environment\n"
           << "  variable. The default is 'gfortran'.\n"
           << "  If invoked with no input files, f18 reads source code from\n"
           << "  stdin and runs with -fdebug-measure-parse-tree -funparse.\n"
           << "\n"
           << "f18 options:\n"
           << "  -Mfixed | -Mfree | -ffixed-form | -ffree-form   force the "
if (arg.empty()) {
           << "  -fdebug-dump-symbols\n"
           << "  -fdebug-resolve-names\n"
           << "  -fdebug-instrumented-parse\n"
           << "  -fdebug-no-semantics  disable semantic checks\n"
           << "  -fget-definition\n"
           << "  -fget-symbols-sources\n"
           << "  -v -c -o -I -D -U    have their usual meanings\n"
           << "  -help                print this again\n"
-          << "Unrecognised options are passed through to the external compiler\n"
+          << "Unrecognised options are passed through to the external "
+             "compiler\n"
           << "set by F18_FC (see defaults).\n";
       return exitStatus;
     } else if (arg == "-V" || arg == "--version") {
       return printVersion();
     } else {
       driver.F18_FCArgs.push_back(arg);
       if (arg == "-v") {
         if (args.size() > 1) {
for (const auto &path : fortranSources) {
     }
   }
   for (const auto &path : otherSources) {
     std::string relo{CompileOtherLanguage(path, driver)};
     if (!driver.compileOnly && !relo.empty()) {
       objlist.push_back(relo);
     }
   }
-  if (!objlist.empty()) {
+  if (!driver.compileOnly && !objlist.empty()) {
     Link(liblist, objlist, driver);
   }
   return exitStatus;
 }