build: remove tab from spdk_lib_list_to_files

The tab inside the define ends up in the output when called, which leads
to problems if the output is quoted (the tab will be treated as part of
the filename).

Change-Id: I1038e1650a74861660fa4164dbde065217bc7b99
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/387631


Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>