Makefile: add Minix configuration options.

Makefile: add Minix configuration options.

Add a $(uname_S) case for Minix with the correct options.

Minix's linker needs all libraries specified explicitly.
Add NEEDS_SSL_WITH_CURL to add -lssl when using -lcurl.
Add NEEDS_IDN_WITH_CURL to add -lidn when using -lcurl.

When NEEDS_SSL_WITH_CURL is defined and NEEDS_CRYPTO_WITH_SSL
is defined, add -lcrypt to CURL_LIBCURL.

Change OPENSSL_LINK to OPENSSL_LIBSSL in the
NEEDS_CRYPTO_WITH_SSL conditional in the libopenssl
section. Libraries go in OPENSSL_LIBSSL, OPENSSL_LINK
is for linker flags.

Signed-off-by: Thomas Cort <tcort@minix3.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>