avoid adding -m32 to various variables multiple times aka, multiple inclusions.

branches: 1.1.2; 1.1.6;
- move -m32 style compat into "m32.mk"
- new Makefile.compat has mostly only the basics now

Catchup with rmind-uvmplock merge.

Apply patch (requested by mrg in ticket #1499):

src/compat version 2. this allows building any number of alternate
library / program target ABIs. rather than duplicating the list of
subdirs and Makefiles to build, it re-traverses the necessary ones.
details:
- add support for MAKEDIRTARGETENV to share/mk
- renames LD32DIR to MLIBDIR
- fixes library builds for some subdirs (more was built than needed)
- fixes /bin & /sbin apps in compat mode
- reduces complexity in src/compat and the rest of the tree
- updates ldd netbsd32 support

file m32.mk was added on branch netbsd-5 on 2011-01-06 05:19:55 +0000