fix misspelling of a legacy macro name in sys/param.h

fix missing parens in bit op macros (param.h)

and another bug in setbit, etc. macros..

fix typo in sys/param.h that broke setbit, etc. macros

this is all junk, but some programs use it.

legacy junk compatibility grab-bag

- add the rest of the junk traditionally in sys/param.h
- add prototypes for some nonstandard functions
- add _GNU_SOURCE to their source files so the compiler can check proto

add MIN/MAX macros to sys/param.h

this is a nonstandard junk header anyway, so just do what apps expect..

make sys/param.h not depend on PATH_MAX and NAME_MAX

this is a nonstandard header used only by backwards programs, but for
some reason it's extremely popular. the recent namespace cleanup fixes
broke it, because PATH_MAX and NAME_MAX will not be defined unless an
approriate feature test macro has been defined. moreover, it's too
late to just #define _GNU_SOURCE in param.h, since limits.h may have
already been included.

let's just hard-code standard values and be done with it.

initial check-in, version 0.5.0