Get rid of dirty-pages list in MDBX_WRITEMAP mode

[erthink]

libmdbx/src/options.h

Lines 112 to 120 in c15ad25

	/* Basically, this build-option is for TODO. Guess it should be replaced
	* with MDBX_ENABLE_WRITEMAP_SPILLING with the three variants:
	* 0/OFF = Don't track dirty pages at all and don't spilling ones.
	* This should be by-default on Linux and may-be other systems
	* (not sure: Darwin/OSX, FreeBSD, Windows 10) where kernel provides
	* properly LRU tracking and async writing on-demand.
	* 1/ON = Lite tracking of dirty pages but with LRU labels and explicit
	* spilling with msync(MS_ASYNC). */
	#ifndef MDBX_FAKE_SPILL_WRITEMAP