osdc: = is not a delimiter in --crush-location

When parsing the crush location

     --crush-location 'root=default host=hostA'

it must create the vector

     [ 'root=default', 'host=hostA' ]

but the default list of separators of get_str_vec includes = which will
create

     [ 'root', 'default', 'host', 'hostA' ]

instead. Set the list of delimiters to exclude = instead.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #1030 from dachary/wip-crush-location

osdc: = is not a delimiter in --crush-location

Reviewed-by: Sage Weil <sage@inktank.com>