Start libc++ python cleanup and consolidation.

Libc++ frequently creates and uses utilities written in python.
Currently there are python modules under both libcxx/test and
libcxx/util. My goal with these changes is to consolidate them
into a single package under libcxx/utils/libcxx.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294644 91177308-0d34-0410-b5e6-96231b3b80d8

utils/not.py

@@ -0,0 +1,44 @@
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+
+"""not.py is a utility for inverting the return code of commands.
+It acts similar to llvm/utils/not.
+ex: python /path/to/not.py ' echo hello
+    echo $? // (prints 1)
+"""
+
+import distutils.spawn
+import subprocess
+import sys
+
+
+def main():
+    argv = list(sys.argv)
+    del argv[0]
+    if len(argv) > 0 and argv[0] == '--crash':
+        del argv[0]
+        expectCrash = True
+    else:
+        expectCrash = False
+    if len(argv) == 0:
+        return 1
+    prog = distutils.spawn.find_executable(argv[0])
+    if prog is None:
+        sys.stderr.write('Failed to find program %s' % argv[0])
+        return 1
+    rc = subprocess.call(argv)
+    if rc < 0:
+        return 0 if expectCrash else 1
+    if expectCrash:
+        return 1
+    return rc == 0
+
+
+if __name__ == '__main__':
+    exit(main())