Optimization opportunity noted by Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2018-08/msg00828.html
On my platform (Fedora 28 x86-64, AMD Phenom II X4 910e,
user+system time), this improved ‘make compile-always’
performance by 0.4% and shrank text size by a similar amount.
* src/lisp.h (TAGGEDP, lisp_h_TAGGEDP): New macros and function.
(lisp_h_CONSP, lisp_h_FLOATP, lisp_h_SYMBOLP)
(lisp_h_VECTORLIKEP, make_lisp_ptr, STRINGP): Use them.
(lisp_h_FIXNUMP): Use the same idea that lisp_h_TAGGEDP uses.