dist/common/scripts/scylla_util.py: strip double quote from sysconfig parameter
dist/common/scripts/scylla_util.py: strip double quote from sysconfig parameter

Current sysconfig_parser.get() returns parameter including double quote,
it will cause problem by append text using sysconfig_parser.set().

Fixes #3587

Signed-off-by: Takuya ASADA <4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>
Message-Id: <20180706172219.16859-1-4ebfb6f510af412d6e89fefa3ab96d9c8b5e3fff@scylladb.com>

avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,duarten/scylla,avikivity/scylla