Makes our error coverage a little more consistent across the board by
applying it to Linux side of things as well. This also makes it more
consistent with the warning settings in other libraries in the project.
This also updates httplib to 0.7.9, as there are several warning
cleanups made that allow us to enable several warnings as errors.
Since the introduction of this library, numerous improvements have been
made. Notably, many of the warnings we would get by simply including the
library header have now been fixed. This makes it much easier to make
conversion warning an error.