1.0.39.3: support building on darwin x86 and x86-64 without the dlshim

1.0.39.3: support building on darwin x86 and x86-64 without the dlshim

  * x86 config -mmacosx-version-min cleanup

  * remove dlshim feature in make-config.sh

  * fix extern-alien-name and ldso naming conventions

  * kludge in load-cold-foreign-symbol-table to strip off the leading
    #\_ from the nm parsing

  * change dependency on ldso stubs for dlopen and friends to be
    #!-dlshim instead of #!-darwin

  * remove Config.x86-64-darwin9+ and replace with makefile
    conditionals

  * add :dlshim feature for darwin in make-config.sh and rework the
    darwin9+ stuff

  * make grovel-headers.c load genesis/config.h first so that we can
    use the LISP_FEATURE_xxx conditionals earlier