It's a bit lame, but some of our C++ wrapping scripts expect objects to be
typedefed like:
typedef struct _FooClass FooClass;
struct {} _FooClass;
Rather than:
typedef struct {} FooClass;
Functionally they're the same, but the former makes our lives easier in the
short term
GResolver provides asynchronous (and synchronous-but-cancellable) APIs
for resolving hostnames, reverse-resolving IP addresses back to
hostnames, and resolving SRV records. Part of #548466.
