in the ISC__BUFFER_PUTUINT*() macros. [RT #592]

This is the basically the same change made to buffer.c before the macros
were created:

   revision 1.18
   date: 1999/09/23 17:54:57;  author: tale;  state: Exp;  lines: +4 -4
   Shut up MSVC++ compiler warning about loss of precision when assigning
   8 bits masked out of a 32 bit int to individual bytes.

Also, an #if 0 around "#define ISC_BUFFER_USEINLINE" was removed, per the
ISC coding style, and instead a comment was used to disable the definition.