* lisp.h (make_gap_1): New prototype.

* lisp.h (make_gap_1): New prototype.
* buffer.h (GAP_BYTES_DFL, GAP_BYTES_MIN): New macros for the special
gap size values.
* editfns.c (Fbuffer_size): Rename from Fbufsize to fit the common
naming convention.
(syms_of_editfns): Adjust defsubr.  Drop commented-out obsolete code.
* insdel.c (make_gap_larger): Use GAP_BYTES_DFL.
(make_gap_smaller): Use GAP_BYTES_MIN.  Adjust comment.
(make_gap_1): New function to adjust the gap of any buffer.
* coding.c (coding_alloc_by_making_gap): Use it.
* buffer.c (compact_buffer): Likewise.  Use BUF_Z_BYTE, BUF_GAP_SIZE,
GAP_BYTES_DFL and GAP_BYTES_MIN.  Adjust comment.