fstests: convert top level files and tools to SPDX

fstests: convert top level files and tools to SPDX

Scripted conversion, see script in initial SPDX license commit
message. Many files required touch-ups after the script had run
because of the old and widely different formats. most touchups were
to remove excess empty comment lines the script left behind.

Signed-off-by: Dave Chinner <dchinner@redhat.com>