Use bread() etc instead of fread() for reading/writing to client.

Move the count of bytes sent into the buffering routines.
Rewrite the buffering routines to provide bputc(), bgetc() macros.

Submitted by: drtr@ast.cam.ac.uk (David Robinson)
Obtained from: 110a.buff.patch


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@76333 13f79535-47bb-0310-9956-ffa450edef68