(CFACT-68) Add -Wextra only if the platform is not solaris

The gcc built on solaris complains of problems in compiling logging.cc when
-Wextra is enabled in cfacter. This seems related to https://svn.boost.org/trac/boost/ticket/8811
which complains of same errors. This patch turns off -Wextra when the OS detected is SunOS
(CFACT 68) Use struct utsname when referring to utsname

The utsname is a structure exposed in <sys/utsname.h> unfortunately, in
Solaris, there is a global variable called utsname, which makes the use of
utsname as a type illegal. This patch changes the invocation to `struct utsname`
(CFACT 68) Provide a skeletal add_platform_facts

This comes in in CFACT 70