commit 266c16ff535a0d7fc89add6db3c13a879be6cdd5
author Nicolas Iooss <nicolas.iooss@m4x.org> Sun Oct 30 22:27:22 2016 +0100
committer Stephen Smalley <sds@tycho.nsa.gov> Mon Oct 31 12:46:54 2016 -0400
tree 31d101d378f1f050f2db8177c95f526dcbefdfc9
parent cb68b534e3c6864c582560033a09e1fee742b950

policycoreutils: semodule_package: do not fail with an empty fc file

When running sepolgen tests on a Linux 4.7 kernel, one test fails with
the following message:

    /usr/bin/semodule_package:  Failed to mmap
    tmp/module_compile_test.mod.fc:  Invalid argument

The .fc file is empty, which is why it cannot be used with mmap().
Anyway the current code supports empty files (with if() conditions in
main()) so do not try to mmap an empty file in file_to_data().

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>