RPM specfile: remove duplicate modbus block
RPM specfile: remove macro accidentally re-added when handling merge conflict
RPM specfile: remove define accidentally re-added when handling merge conflict
RPM specfile: add missing %files section for modbus plugin

complement to a781eb2c5
RPM specfile: support for RHEL7
RPM specfile: fix bogus dates

modern rpmbuild versions appear to be more strict on this point.
RPM specfile: enable netlink plugin on RHEL > 5
processes plugin: Limit the buffer size used for command line matching.

ARG_MAX is quite big on many systems, for example >100 kByte on
GNU/Linux. This is a problem for systems with tight memory constraints,
for example embedded devices.

This patch uses at most 4 kByte for this, which out to be enough for the
vast majority of users. Users with specific requirements can compile
with "CMDLINE_BUFFER_SIZE=${LOTS}" in their CPPFLAGS to override this
default.

Fixes: #652
Merge remote-tracking branch 'github/master'
Merge branch 'collectd-5.3' into collectd-5.4

Conflicts:
	contrib/redhat/collectd.spec
RPM specfile: enable lvm plugin on RHEL7
Merge branch 'collectd-5.4'
RPM specfile: take all new plugins and dependencies in account
src/configfile.c: Fix the default interval setting.

Also fixes a bug in global_option_get_time(): Values smaller than or
equal to zero are illegal and the default value should be returned.
Thanks to @anandkarthik for spotting this!

Fixes: #727
merge with upstream