Compilation warnings in net_db.c

[Eli Zaretskii]

While compiling net_db.c from Guile 2.0.12 with MinGW, I get a bunch
of warnings such as this one:

   net_db.c:454:20: warning: 'sym_ai_passive' defined but not used 
[-Wunused-variable]
    SCM_VARIABLE_INIT (sym_ai_passive, "AI_PASSIVE",
                       ^
   ../libguile/snarf.h:82:29: note: in definition of macro 'SCM_SNARF_HERE'
    #  define SCM_SNARF_HERE(X) X
                                ^
   net_db.c:454:1: note: in expansion of macro 'SCM_VARIABLE_INIT'
    SCM_VARIABLE_INIT (sym_ai_passive, "AI_PASSIVE",
    ^

AFAICT, these SCM_VARIABLE_INIT calls wind up declaring static
variables that are not used in net_db.c.  Is that what's supposed to
happen, or do I need to look more into this?  Do people get these
warnings on Posix platforms?