Define getaddrinfo() and freeaddrinfo() as functions instead of wrappers

Define getaddrinfo() and freeaddrinfo() as functions instead of wrappers

Commit 28138d6d added getaddrinfo() and freeaddrinfo() as wrappers. However,
it's not necessary for a source file to include the netdb.h header where they
are defined when it uses them. So their definitions are needed as functions and
not as macros.

Signed-off-by: Bogdan Lascu <lascu.bogdan96@gmail.com>
Signed-off-by: Costin Lupu <costin.lupu@cs.pub.ro>
Reviewed-by: Charalampos Mainas <charalampos.mainas@neclab.eu>