Add --enable-pgo option to build clang with PGO

tools/clang/scripts/package.py

Index: tools/clang/scripts/package.py
diff --git a/tools/clang/scripts/package.py b/tools/clang/scripts/package.py
index d0aded21d6e3bef6d325687c6006124b02b8711c..dc507d1d780d37b4587ebd67a6b42330e9c7403a 100755
--- a/tools/clang/scripts/package.py
+++ b/tools/clang/scripts/package.py
@@ -24,7 +24,14 @@ LLVM_BOOTSTRAP_DIR = os.path.join(THIRD_PARTY_DIR, 'llvm-bootstrap')
 LLVM_BOOTSTRAP_INSTALL_DIR = os.path.join(THIRD_PARTY_DIR,
                                           'llvm-bootstrap-install')
 LLVM_BUILD_DIR = os.path.join(THIRD_PARTY_DIR, 'llvm-build')
-LLVM_RELEASE_DIR = os.path.join(LLVM_BUILD_DIR, 'Release+Asserts')
+
+if sys.platform == 'win32':
+  LLVM_RELEASE_DIR = os.path.join(LLVM_BUILD_DIR, 'Release+Asserts', 'tools',
+                                  'clang', 'stage2-bins')
+else:
+  LLVM_RELEASE_DIR = os.path.join(LLVM_BUILD_DIR, 'Release+Asserts', 'tools',
+                                  'clang', 'stage2-instrumented-bins', 'tools',
+                                  'clang', 'stage2-bins')
 LLVM_LTO_GOLD_PLUGIN_DIR = os.path.join(THIRD_PARTY_DIR, 'llvm-lto-gold-plugin')
 BINUTILS_LIB_DIR = os.path.join(THIRD_PARTY_DIR, 'binutils', 'Linux_x64',
                                 'Release', 'lib')
@@ -228,12 +235,12 @@ def main():
     shutil.rmtree(LLVM_BOOTSTRAP_INSTALL_DIR, ignore_errors=True)
     shutil.rmtree(LLVM_BUILD_DIR, ignore_errors=True)
 
-    opt_flags = []
+    opt_flags = ['--bootstrap' if sys.platform == 'win32' else '--enable-pgo']
     if sys.platform.startswith('linux'):
       opt_flags += ['--lto-gold-plugin']
+
     build_cmd = [sys.executable, os.path.join(THIS_DIR, 'update.py'),
-                 '--bootstrap', '--force-local-build',
-                 '--run-tests'] + opt_flags
+                 '--force-local-build', '--run-tests'] + opt_flags
     TeeCmd(build_cmd, log)
 
   stamp = open(STAMP_FILE).read().rstrip()
@@ -321,7 +328,7 @@ def main():
 
   # Copy libc++ headers.
   if sys.platform == 'darwin':
-    shutil.copytree(os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR, 'include', 'c++'),
+    shutil.copytree(os.path.join(LLVM_RELEASE_DIR, 'include', 'c++'),
                     os.path.join(pdir, 'include', 'c++'))
 
   # Copy tcmalloc from the binutils package.