Update unix Makefile template to handle paths with spaces
Fixes #4668 (on unix-like platforms)
Testing:
rm -rf "$HOME/tmp/beforespace afterspace"
./Configure -Werror --strict-warnings --prefix="$HOME/tmp/beforespace afterspace"
make -j6 update
make -j6
make install
make test
Reviewed-by: Richard Levitte <levitte@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/21821)