Need to pass va_list as a reference to vsyslog.  This is because va_list is a structure in some compilers and passing of structures in the NuttX sycalls does not work.

There is now one-and-only-one copy of syslog_putc.  It is in the SYSLOG channel logic and can redirect syslog output as needed.  All former syslog_putc versions were renamed and the corresponding SYSLOG device initializaiton now calls syslog_channel()

Some renaming so that future features will fit in better; If the architecture provides its only system logging (via CONFIG_ARCH_SYSLOG), then syslog_initialize() is stubbed out

Move RAMLOG initialize from up_initialilize.c files to syslog_initialize().  up_initialize.c files now call syslog_initialize() unconditionally

Some higher level SYSLOG features are disabled if the architecture-specific logic provides its own SYSLOG functionality

Add a hook before the existing syslog_initialize() call; rename the old syslog_initialize() to syslog_dev_initialize().

Move the OS intensive part of vsyslog and vlowsyslog to drivers/syslog/vsyslog.c and vlowsyslog.c.  Also move lib_syslogstrem to drivers/syslog/syslogstream.c

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