[fir] Get rid of the global option in FIRBuilder

[clementval]

Summary

Replace the global option nameLengthHashSize with a constexpr
with the same name. The option was not used in fir-dev so switching
to a constexpr is fine.

[kiranchandramohan]

Was the suggestion to use a dialect attribute/constant?

[clementval]

In D114630#3158446, @kiranchandramohan wrote:

Was the suggestion to use a dialect attribute/constant?

It is currently not used so always 32 so a simple constexpr should be enough, no?

[kiranchandramohan]

In D114630#3158447, @clementval wrote:

In D114630#3158446, @kiranchandramohan wrote:

Was the suggestion to use a dialect attribute/constant?

It is currently not used so always 32 so a simple constexpr should be enough, no?

Ah OK, if it is not used then it is fine with me.

flang/lib/Optimizer/Builder/FIRBuilder.cpp

 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
 #include "flang/Optimizer/Support/FatalError.h"
 #include "flang/Optimizer/Support/InternalNames.h"
 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/MD5.h"
 
-static llvm::cl::opt<std::size_t>
-    nameLengthHashSize("length-to-hash-string-literal",
-                       llvm::cl::desc("string literals that exceed this length"
-                                      " will use a hash value as their symbol "
-                                      "name"),
-                       llvm::cl::init(32));
+static constexpr std::size_t nameLengthHashSize = 32;
 
 mlir::FuncOp fir::FirOpBuilder::createFunction(mlir::Location loc,
                                                mlir::ModuleOp module,
                                                llvm::StringRef name,
                                                mlir::FunctionType ty) {
   return fir::createFuncOp(loc, module, name, ty);
 }