Misc: Trim and consolidate header file usage

Misc: Trim and consolidate header file usage

Refactor libusbi.h to include the set of common header files needed by
every main source file in the library and change these source files to
include libusbi.h first, followed by any non-common headers. Including
libusbi.h first ensures that the config definitions are pulled in and
will eliminate redundant includes in the individual sources files.

Also clean up some whitespace errors and remove unnecessary definitions
in the manually generated config.h files.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>