[asan_symbolize] Move argument parser epilog text into script doc comment.

[delcypher]

Summary

This will make it easier to expand on the documentation in the future
that avoids cluttering the code.

rdar://problem/49476995

compiler-rt/trunk/lib/asan/scripts/asan_symbolize.py

 #!/usr/bin/env python
 #===- lib/asan/scripts/asan_symbolize.py -----------------------------------===#
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 #===------------------------------------------------------------------------===#
+"""
+Example of use:
+  asan_symbolize.py -c "$HOME/opt/cross/bin/arm-linux-gnueabi-" -s "$HOME/SymbolFiles" < asan.log
+"""
 import argparse
 import bisect
 import getopt
 import logging
 import os
 import re
 import subprocess
 import sys
def setup_logging():
   return unparsed_args
 
 
 if __name__ == '__main__':
   remaining_args = setup_logging()
   parser = argparse.ArgumentParser(
       formatter_class=argparse.RawDescriptionHelpFormatter,
       description='ASan symbolization script',
-      epilog='Example of use:\n'
-             'asan_symbolize.py -c "$HOME/opt/cross/bin/arm-linux-gnueabi-" '
-             '-s "$HOME/SymbolFiles" < asan.log')
+      epilog=__doc__)
   parser.add_argument('path_to_cut', nargs='*',
                       help='pattern to be cut from the result file path ')
   parser.add_argument('-d','--demangle', action='store_true',
                       help='demangle function names')
   parser.add_argument('-s', metavar='SYSROOT',
                       help='set path to sysroot for sanitized binaries')
   parser.add_argument('-c', metavar='CROSS_COMPILE',
                       help='set prefix for binutils')