Remove -m32/-m64 args from makefiles.

[waywardmonkeys]

We detect machinetype and build for the native CPU type as it
is, so we don't need to repeat this here in each makefile.

[waywardmonkeys]

I'm adding .mk files that we can include, one for each compiler, so that I can configure things like dependency flags correctly for each compiler.

That would be easier if there weren't 32 / 64 bit flags being given, especially as I don't think they should be needed.

[nbriggs]

Generally, I agree with this. I have a problem, though, in what ends up actually happening -- on my 10.11 (El Capitan) mac, the compiler default is 64-bit but it supports 32-bit as well and we have bin/machinetype reporting "386" rather than x86_64. On the SPARC Solaris system, bin/machinetype reports "sparc" (not sparc64, or sparcv9), and 3 different C compilers with 7 different versions -- some of them default to 32-bit (sparcv8 instruction set), some default to 64-bit (sparcv9 instruction set).

I'd like to be able to more easily pick the compiler and options that get used. It would also be great to have a consistent method to add extra (or change existing) options -- adding -Wxxx or -fxxx, change the -On and so on.

[masinter]

on my mac mini I can do

arch -x86_64 ./makeright x

and compile maiko x86 binaries into darwin.x86_64/lde and ldex

[nbriggs]

Yes, I can do arch -x86_64 ./makeright x on my MacBook Pro, but if I do arch -i386 ./makeright x it produces

arch: posix_spawnp: ./makeright: Bad CPU type in executable

because all the executables used to create a 32-bit lde are in fact 64-bit executables, and for most other systems it's more like the -m32/-m64 (or --target=<target-triple> for cross-compiling).

[waywardmonkeys]

On macOS, it is usually -arch i386 and -arch x86_64 and -arch arm64 ... I'm still thinking about what to do about this patch.