[RocksDB] Fix build. Removed deprecated option --mmap_read from db_crashtest

Summary: As title

Test Plan: db_crashtest

Reviewers: vamsi, emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11271

tools/db_crashtest.py

@@ -66,7 +66,6 @@ def main(argv):
         run_had_errors = False
         additional_opts = ' --disable_seek_compaction=' + \
                           str(random.randint(0, 1)) + \
-                          ' --mmap_read=' + str(random.randint(0, 1)) + \
                           ' --block_size=16384 ' + \
                           ' --cache_size=1048576 ' + \
                           ' --open_files=500000 ' + \

tools/db_crashtest2.py

@@ -71,7 +71,6 @@ def main(argv):
         run_had_errors = False
         additional_opts = ' --disable_seek_compaction=' + \
                           str(random.randint(0, 1)) + \
-                          ' --mmap_read=' + str(random.randint(0, 1)) + \
                           ' --block_size=16384 ' + \
                           ' --cache_size=1048576 ' + \
                           ' --open_files=500000 ' + \