Wire --llvm-include-tests in build-script

This was apparently missing in the migration of the llvm product
from build-script-impl to build-script,

Author: edymtt

utils/build-script-impl

@@ -175,7 +175,6 @@ KNOWN_SETTINGS=(
     skip-clean-xctest                             "0"               "skip cleaning the xctest build"
 
     ## Test Options
-    llvm-include-tests                            "1"               "Set to true to generate testing targets for LLVM. Set to true by default."
     long-test                                     "0"               "set to run the long test suite"
     only-executable-test                          ""                "only run the executable variant of the swift lit tests"
     stress-test                                   "0"               "set to run the stress test suite"

utils/build_swift/build_swift/driver_arguments.py

@@ -1421,8 +1421,14 @@ def create_argument_parser():
                 'Can be called multiple times '
                 'to add multiple such options.')
 
-    option('--no-llvm-include-tests', toggle_false('llvm_include_tests'),
-           help='do not generate testing targets for LLVM')
+    with mutually_exclusive_group():
+        set_defaults(llvm_include_tests=True)
+
+        option('--no-llvm-include-tests', toggle_false('llvm_include_tests'),
+               help='do not generate testing targets for LLVM')
+
+        option('--llvm-include-tests', toggle_true('llvm_include_tests'),
+               help='generate testing targets for LLVM')
 
     option('--llvm-cmake-options', append,
            type=argparse.ShellSplitType(),

utils/build_swift/tests/expected_options.py

@@ -557,7 +557,8 @@ class BuildScriptImplOption(_BaseOption):
     SetOption('--no-swift-stdlib-strict-availability',
               dest='swift_stdlib_strict_availability', value=False),
 
-    SetFalseOption('--no-llvm-include-tests', dest='llvm_include_tests'),
+    DisableOption('--no-llvm-include-tests', dest='llvm_include_tests'),
+    EnableOption('--llvm-include-tests', dest='llvm_include_tests'),
 
     SetTrueOption('--install-back-deploy-concurrency',
                   dest='install_backdeployconcurrency'),