Move lib{numa,dw,zstd} defines to RTS configure

Clean up the m4 to handle the auto case always and be more consistent. Also simplify the CPP --- we should always have both headers if we are using libnuma.

"side effects" (AC_DEFINE, and AC_SUBST) are removed from the macros to better separate searching from actions taken based on search results. This might seem overkill now, but will make shuffling logic between configure scripts easier later.

The macro comments are converted from dnl to # following the recommendation in https://www.gnu.org/software/autoconf/manual/autoconf-2.71/html_node/Macro-Definitions.html

Progress towards #17191 (closed)