tlsdate: Allow explicitly disabling seccomp support

Allow building without seccomp filter support if requested. This is
currently not the case when cross-compiling, where seccomp support
is default assumed.

BUG=chromium:358444
TEST='USE=-seccomp emerge-mipsel-o32-generic tlsdate' now builds.

CQ-DEPEND=CL:194323

Change-Id: I105d9a7238f49c87ee4c060ca5ef160239628410
Reviewed-on: https://chromium-review.googlesource.com/194289
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Will Drewry <wad@chromium.org>
Tested-by: Gaurav Shah <gauravsh@chromium.org>
Commit-Queue: Gaurav Shah <gauravsh@chromium.org>
1 file changed