- eliminate ambiguities between GNU-ish and SysV-ish make flavors;
- switch [back] to -e;
- fold/unify rules;

This is follow-up to the patch introducing common BUILDENV. Idea is
to collect as much parameters in $(TOP) as possible and "strip" lower
Makefiles for most variables [and thus makes them more readable].

dynamic loading is consistent with respect to engine ids.

[most importantly] put back dependencies accidentaly eliminated in
check-in #13342.

during "make errors" and thus during "make update".

Fix lots of bugs that util/ck_errf.pl can detect automatically.
Various others of these are still left to fix; that's why
"make update" will complain loudly when run now.

install to a different location than it had created. (BTW, VMS will need a
matching fix in eng_list.c.) Note, these aren't ssl-specific, so I'm
putting "engines/" into the libs directory rather than at the "--prefix"
level or inside "ssl/".

think that proper Makefile clean-up is required.

key operations using the GMP library. The default is not to build (or use)
this code unless OPENSSL_USE_GMP is defined (because it will impose header
and linker dependencies that might need specifying too).

- define a HERE variable to indicate where the source tree is (used
  very little right now)
- make more use of copying and making attribute changes to {file}.new,
  and then move it to {file}
- use 'mv -f' to avoid all those questions to the user when the file
  in question doesn't have write attributes for that user.

depend upon.