Expand the use of the sys/unix Makefiles to be used for both normal
local builds and installs, as well as cross-compiles for other
platforms/targets.
Up until now, the primary unix Makefiles have treated util/host-side
component compiles, links and target object files just the same as
the game component compiles, links, and target object files.
Unfortunately, that meant that cross-compile effort typically had
to re-invent Makefiles specific to the cross-compile, creating a
maintenance burden and deviation from the typical local unix build
and providing a daunting obstacle to those that want to establish
build for a target environment/platform.
This change distinguishes between util/host-side component builds,
links, and component builds and targets object files destined for
the game (and other target platforms) in the Makefiles.
In theory, this will ease the effort for people that want to try to
resurrect NetHack perhaps on an old platform where it is no longer
viable to build NetHack-3.7 on the platform itself using old, outdated
compile tools, possibly with an old, outdated C dialect.
Some details:
- Game-related targets in the Makefiles (as opposed to util/host-side
targets that will be executed on the host), which could be destined
for another platform in a cross-compile scenario are prefixed with
$(TARGETPFX) so that they are distinguished.
The default scenario where no cross-compiler is involved, is to
define TARGETPFX to nothing, and therefore meant to have no effect.
- Game-related compile and link commands in the Makefiles and their
associated command line flags are distinguished from util/host-side
compile and link commands in the Makefiles by using $(TARGET_CC),
$(TARGET_CFLAGS), $(TARGET_LINK), $(TARGET_LFLAGS), $(TARGET_CXX),
$(TARGET_CXXFLAGS), $(TARGET_LIBS).
Those are used in the Makefile in place of $(CC), $(CFLAGS), $(LINK),
$(LFLAGS), $(CXX), $(CXXFLAGS), $(LIBS).
The default scenario where no cross-compiler is involved, defines
the TARGET_ version of those Makefile variables to match their
typical non-TARGET_ ounterparts.
- The dependency lists in the Makefiles includes the $(TARGETPFX)
prefix for stuff that would potentially be produced from a
cross-compile build.
- It adds pregame targets and $(PREGAME) variable, so that hints files
can add some additional stuff if required for a cross-compile
scenario.
The default scenario where no cross-compiler is involved doesn't
do anything for $(PREGAME).
- It adds $(BUILDMORE) target and variable, so that hints files
can add some additional things to be built for a cross-compile
scenario.
- It adds a "package" target and $(PACKAGE) variable, so that hints files
can add steps for the target platform in a cross-compile
scenario.
The "install" target assumes local build and placement and
isn't really applicable to a cross-compile scenario where the results
really just need to be bundled up for transport to the target platform.
- Also, this adds a pair of include files that can be updated with some
cross-compile recipes as they evolve. They are named "cross-pre.2020"
(for stuff to be included in the PRE section) and "cross-post.2020"
for stuff to be included in the POST section via sys/unix/setup.sh.
Those are included in sys/unix/hints/linux.2020 and
sys/unix/hints/macOS.2020 hints files.
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