Until now, the collection of vlog modules supported by a given OVS program
was not specific to that program. That means that, for example, even
though ovs-dpctl does not have anything to do with jsonrpc, it still has
a vlog module for it. This is confusing, at best.
This commit fixes the problem on some systems, in particular on ones that
use GCC and the GNU linker. It uses the feature of the GNU linker
described in its manual as:
If an orphaned section's name is representable as a C identifier then
the linker will automatically see PROVIDE two symbols: __start_SECNAME
and __end_SECNAME, where SECNAME is the name of the section. These
indicate the start address and end address of the orphaned section
respectively.
Systems that don't support these features retain the earlier behavior.
This commit also fixes the annoyance that modifying lib/vlog-modules.def
causes all sources files that #include "vlog.h" to recompile.
It's more convenient if clients don't have to initialize modules
explicitly.
The most important part of this change is to initialize the default
log levels statically. Previously, by initializing log levels only
from vlog_init(), all the log levels appeared to be VLL_EMER (0) if
vlog_init() was accidentally not called at all. This was not intended
behavior, so this commit fixes it.
This commit also fixes up a few test programs whose tests accidentally
depended on this behavior, by making them explicitly turn off log
messages that were implicitly turned off before.
Since the timeval module now initializes itself on-demand, there is no
longer any need to initialize it explicitly, or to provide an interface to
do so.
