LangOptions: tie NoncopyableGenerics to build

There were a handful of different places trying to enable the
feature-flag when the stdlib has been built with the feature enabled.
This change cleans that up and unifies it in one spot for all sub-tools
like sil-opt and sil-func-extractor to pick-up.

Author: kavon

lib/Basic/LangOptions.cpp

@@ -47,6 +47,13 @@ LangOptions::LangOptions() {
 #endif
 
   // Note: Introduce default-on language options here.
+
+  // Default-on NoncopyableGenerics when the build-script setting is enabled.
+  if (SWIFT_ENABLE_EXPERIMENTAL_NONCOPYABLE_GENERICS) {
+    Features.insert(Feature::NoncopyableGenerics);
+    EnableExperimentalAssociatedTypeInference = true;
+  }
+
   // Enable any playground options that are enabled by default.
 #define PLAYGROUND_OPTION(OptionName, Description, DefaultOn, HighPerfOn) \
   if (DefaultOn) \

lib/DriverTool/sil_opt_main.cpp

@@ -645,8 +645,6 @@ int sil_opt_main(ArrayRef<const char *> argv, void *MainAddr) {
     Invocation.getLangOptions().enableFeature(
         Feature::OldOwnershipOperatorSpellings);
   }
-  if (SWIFT_ENABLE_EXPERIMENTAL_NONCOPYABLE_GENERICS)
-    Invocation.getLangOptions().enableFeature(Feature::NoncopyableGenerics);
 
   Invocation.getLangOptions().BypassResilienceChecks =
       options.BypassResilienceChecks;

lib/Frontend/CompilerInvocation.cpp

@@ -895,11 +895,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   Opts.enableFeature(Feature::LayoutPrespecialization);
 
-  if (SWIFT_ENABLE_EXPERIMENTAL_NONCOPYABLE_GENERICS) {
-    Opts.enableFeature(Feature::NoncopyableGenerics);
-    Opts.EnableExperimentalAssociatedTypeInference = true;
-  }
-
   Opts.EnableAppExtensionLibraryRestrictions |= Args.hasArg(OPT_enable_app_extension_library);
   Opts.EnableAppExtensionRestrictions |= Args.hasArg(OPT_enable_app_extension);
   Opts.EnableAppExtensionRestrictions |= Opts.EnableAppExtensionLibraryRestrictions;

tools/swift-ide-test/swift-ide-test.cpp

@@ -4426,9 +4426,6 @@ int main(int argc, char *argv[]) {
     InitInvok.getLangOptions().EnableExperimentalStringProcessing = true;
   }
 
-  if (SWIFT_ENABLE_EXPERIMENTAL_NONCOPYABLE_GENERICS)
-    InitInvok.getLangOptions().enableFeature(Feature::NoncopyableGenerics);
-
   if (!options::Triple.empty())
     InitInvok.setTargetTriple(options::Triple);
   if (!options::SwiftVersion.empty()) {