[Build System: build-script] Remove the debug module from swift_build_support.

utils/build-script

@@ -27,7 +27,6 @@ from build_swift.build_swift import presets
 import six
 
 from swift_build_support.swift_build_support import (
-    debug,
     diagnostics,
     products,
     shell,
@@ -71,6 +70,25 @@ class JSONDumper(json.JSONEncoder):
         return six.text_type(o)
 
 
+def print_xcodebuild_versions(file=sys.stdout):
+    """
+    Print the host machine's `xcodebuild` version, as well as version
+    information for all available SDKs.
+    """
+    version = shell.capture(
+        ['xcodebuild', '-version'], dry_run=False, echo=False).rstrip()
+    # Allow non-zero exit codes.  Under certain obscure circumstances
+    # xcodebuild can exit with a non-zero exit code even when the SDK is
+    # usable.
+    sdks = shell.capture(
+        ['xcodebuild', '-version', '-sdk'], dry_run=False, echo=False,
+        allow_non_zero_exit=True).rstrip()
+    fmt = '{version}\n\n--- SDK versions ---\n{sdks}\n'
+
+    print(fmt.format(version=version, sdks=sdks), file=file)
+    file.flush()
+
+
 class BuildScriptInvocation(object):
 
     """Represent a single build script invocation."""
@@ -1116,7 +1134,7 @@ def main_normal():
 
     # Show SDKs, if requested.
     if args.show_sdks:
-        debug.print_xcodebuild_versions()
+        print_xcodebuild_versions()
 
     if args.dump_config:
         print(JSONDumper().encode(invocation))