perf tools: Add compress.h for the *_decompress_to_file() headers

Out of util.h, the implementations were already in separate files, that
are built conditionally.

Link: http://lkml.kernel.org/n/tip-0ur7szxsb59f8758kfe63prb@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>