Consider including all compile flags in "named -V" output

The following discussion from !985 (merged) should be addressed:

• @michal started a discussion: (+2 comments)

  Nit: I think this would be better written as:

  echo "CFLAGS: $STD_CFLAGS $CFLAGS"

  because that is the order that Automake uses in the Makefiles it generates with AM_CFLAGS set to $(STD_CFLAGS).

  Also, something for the future perhaps, but it would be nice to see all (effective) CFLAGS/CPPFLAGS/LDFLAGS in named -V output, not just those overridden using environment variables set when ./configure is run.