Can't change config settings via struct initializer

The freegeoip example tries to set some config settings directly via a
struct literal, but this does not appear to be a supported way to do
that since the first thing lwan_init() does is overwrite it with its own
defaults. Someone looking through the examples might be misled by this.
Include missing headers

stddef.h for size_t
time.h for struct timespec and time_t
stdbool.h for bool
stdint.h for int32_t
Keep indentation style consistent

Most of the lwan-* files use 4 space indentation, so this makes the few
two space identation files consistent with the rest of the code.