Build libcrypto using single-Makefile scheme

libcrypto will now build successfully using GNU Make. Future changes will
bring other libraries in line.
Adapt test/ files to fit single-Makefile scheme
Adapt crypto, ssl shared libs to single-Makefile
Update rehash dependency for single-Makefile
Add 'making TARGET in SDIR...' for single-Makefile
Update FIPS target for single-Makefile
Remove unnecessary test targets; tweak rehash

As of this change, the single-Makefile scheme works when using GNU Make to
build the non-FIPS 'all' and 'test' targets. I verified this by comparing log
output between a build using these changes and a build still using recursive
Make.