lib/lzo: Rename lzo1x_decompress.c to lzo1x_decompress_safe.c

commit b6bec26cea948148a9420e7a0ac337f925de49e7 upstream.

Rename the source file to match the function name and thereby
also make room for a possible future even slightly faster
"non-safe" decompressor version.

Signed-off-by: Markus F.X.J. Oberhumer <markus@oberhumer.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>