observed: parallel build attempts of makedefs that trampled over
one another.
attempted workaround: Add a dependency as per Pat R's suggestion.
observed: Concurrent header file movement collisions were sometimes
causing file busy errors and build failures.
workaround: Eliminate tile.h header file movement from the
Makefile build so that the collisions won't occur with that
particular file. Leave the header file tile.h in win/share as it
is in the distribution and just adjust the include path in the
rule for the specific files that use it.
observed: tiletxt.c created on-the-fly from Makefile echo statements
sometimes resulted in garbled and duplicate content in it when
parallel makes were involved, and that caused a build failure.
workaround: Instead of creating a tiletxt.c on-the-fly via echo
statements in the Makefile, simplify things and use that
same #include "tilemap.c" approach but make it an actual file
in the distribution. That makes it available for other platforms
too.