sbcl: Honor UNLIMIT_RESOURCES and address PaX problems

- Due custom do-{build,test,install} UNLIMIT_RESOURCES were not honored leading
  to:

      //slurp-ucd
      *** - No more room for LISP objects

  errors. Adjust these target to honor UNLIMIT_RESOURCES.
- sbcl does not work with PaX MPROTECT because mmap()s by OR'ing all
  PROT_{EXEC,READ,WRITE}. Unfortunately src/runtime/sbcl is also
  used as part of building needing also `${PAXCTL} +m' in the middle
  of the build.
  Introduce an SBCL_PAXCTL variable (by default `:') via
  patch-src_runtime_GNUmakefile that execute a program against src/runtime/sbcl
  and define it for platforms that have a paxctl tool.
  Mark bin/sbcl with NOT_PAX_MPROTECT_SAFE too.
- Refactor the environment variables injection logic in do-{build,test,install}
  to honor MAKE_ENV and INSTALL_ENV.
- Minor mostly cosmetic adjustments (use ${RM}, not rm)

Bump PKGREVISION

(leot)