[USETUP][SETUPLIB]: Move some INF-related code from usetup to the setuplib. - Move the generic INF_GetDataField() and INF_GetData() helpers to setuplib, and rework them a bit so that they explicitly call setupapi functions (or implementations thereof when being used in usetup); - Rework the headers in accordance; - and Fix compilation in lib/registry.c .
[USETUP][SETUPLIB]: Improve how the Setup* INF APIs are interfaced in the code. Define prototypes compatibles (including their calling convention) to the ones defined by setupapi (.h/.dll) so that it can be possible to either use an internal implementation of these functions (via the inflib library), as currently done, or using imported setupapi functions, as would be done by the future 1st-stage GUI installer.
[SETUPLIB]: Cleanup the registry.c file and use the infsupp.h header.
Fixes build that was technically broken since r75247.