Deduplicate mk_linux.mk with makefile

[examosa]

Relates to #60

mk_linux.mk is almost identical to makefile. Here are their differences:

3,4c3,4
< #   make depend
< #   make
---
> #   make -f mk_linux.mak depend
> #   make -f mk_linux.mak
154,155c154,155
<       $(MAKE) s7
<       $(MAKE) s7c
---
>       $(MAKE) -f mk_linux.mak s7
>       $(MAKE) -f mk_linux.mak s7c
263c263
<       echo "#define MAKEFILE_NAME \"makefile\"" >> settings.h
---
>       echo "#define MAKEFILE_NAME \"mk_linux.mak\"" >> settings.h

I have updated mk_linux.mk to be a symlink pointing to makefile and updated the latter to work for either invocation.

• Updated the all target to list s7 and s7c as prerequisites rather than recursively invoking $(MAKE)
• Used the built-in MAKEFILE_LIST variable to derive makefile_name rather than hard-coding it.

Let me know your thoughts!

[ThomasMertes]

Thank you for your pull request.

The two files makefile and mk_linux.mak are separate on purpose. For several platforms the build documentation suggest copying a mk_*.mak file to makefile. If mk_linux.mak links to makefile the copying would change mk_linux.mak too. This would make it impossible to later copy mk_linux.mak to makefile in order to compile under Linux.

[examosa]

Since makefile itself is also designed for compiling under Linux, would it make more sense to remove mk_linux.mak entirely? Alternatively, I could create a separate GNUmakefile that both makefile and mk_linux.mak are linked to.
Ultimately the goal is to consolidate most of the redundancy across the various POSIX makefiles to reduce their maintenance burden; there are more details in this DeepWiki chat.