RequirementMachine: Enable flags directly in LangOptions

This enables requirement machine minimization for all tools (SourceKit, etc)
not just the frontend.

Author: slavapestov

include/swift/Basic/LangOptions.h

@@ -528,17 +528,17 @@ namespace swift {
     /// Enable the new experimental protocol requirement signature minimization
     /// algorithm.
     RequirementMachineMode RequirementMachineProtocolSignatures =
-        RequirementMachineMode::Disabled;
+        RequirementMachineMode::Verify;
 
     /// Enable the new experimental generic signature minimization algorithm
     /// for abstract generic signatures.
     RequirementMachineMode RequirementMachineAbstractSignatures =
-        RequirementMachineMode::Disabled;
+        RequirementMachineMode::Verify;
 
     /// Enable the new experimental generic signature minimization algorithm
     /// for user-written generic signatures.
     RequirementMachineMode RequirementMachineInferredSignatures =
-        RequirementMachineMode::Disabled;
+        RequirementMachineMode::Verify;
 
     /// Disable preprocessing pass to eliminate conformance requirements
     /// on generic parameters which are made concrete. Usually you want this

lib/Frontend/CompilerInvocation.cpp

@@ -912,10 +912,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.DisableSubstSILFunctionTypes =
       Args.hasArg(OPT_disable_subst_sil_function_types);
 
-  Opts.RequirementMachineProtocolSignatures = RequirementMachineMode::Verify;
-  Opts.RequirementMachineInferredSignatures = RequirementMachineMode::Verify;
-  Opts.RequirementMachineAbstractSignatures = RequirementMachineMode::Verify;
-
   if (auto A = Args.getLastArg(OPT_requirement_machine_protocol_signatures_EQ)) {
     auto value = llvm::StringSwitch<Optional<RequirementMachineMode>>(A->getValue())
         .Case("off", RequirementMachineMode::Disabled)

test/IDE/print_ast_tc_decls.swift

@@ -1231,7 +1231,7 @@ extension GenericParams1 where StructGenericBaz: FooProtocol {
   // PASS_PRINT_AST: static func contextualWhereClause2() where StructGenericBaz : FooClass{{$}}
 
   typealias ContextualWhereClause3 = Never where StructGenericBaz: QuxProtocol, StructGenericBaz.Qux == Void
-  // PASS_PRINT_AST: typealias ContextualWhereClause3 = Never where StructGenericBaz : QuxProtocol, StructGenericBaz.Qux == Void{{$}}
+  // PASS_PRINT_AST: typealias ContextualWhereClause3 = Never where StructGenericBaz : QuxProtocol, StructGenericBaz.Qux == (){{$}}
 }
 
 struct GenericParams2<T : FooProtocol> where T : BarProtocol {}