[flang] Removed old option -fdebug-dump-pre-fir (#168008)

This option has long been replaced by `-fc1 -fdebug-dump-pft`. Removed
the old option and updated one test that still used it.

Author: eugeneepshteyn

flang/lib/Lower/Bridge.cpp

@@ -86,10 +86,6 @@
 
 #define DEBUG_TYPE "flang-lower-bridge"
 
-static llvm::cl::opt<bool> dumpBeforeFir(
-    "fdebug-dump-pre-fir", llvm::cl::init(false),
-    llvm::cl::desc("dump the Pre-FIR tree prior to FIR generation"));
-
 static llvm::cl::opt<bool> forceLoopToExecuteOnce(
     "always-execute-loop-body", llvm::cl::init(false),
     llvm::cl::desc("force the body of a loop to execute at least once"));
@@ -7027,8 +7023,6 @@ void Fortran::lower::LoweringBridge::lower(
     const Fortran::semantics::SemanticsContext &semanticsContext) {
   std::unique_ptr<Fortran::lower::pft::Program> pft =
       Fortran::lower::createPFT(prg, semanticsContext);
-  if (dumpBeforeFir)
-    Fortran::lower::dumpPFT(llvm::errs(), *pft);
   FirConverter converter{*this};
   converter.run(*pft);
 }

flang/test/Lower/ifconvert.f90

@@ -1,4 +1,4 @@
-! RUN: bbc -fdebug-dump-pre-fir %s 2>&1 | FileCheck %s
+! RUN: %flang_fc1 -fdebug-dump-pft %s 2>&1 | FileCheck %s
 
 ! Note: PFT dump output is fairly stable, including node indexes and
 !       annotations, so all output is CHECKed.