Do not link with -lcrypto under NO_OPENSSL

With 401857c4 (imap-send: link against libcrypto for HMAC and others,
2010-11-24) we started linking imap-send unconditionally with -lcrypto by
mistake; disable this when we are building under NO_OPENSSL.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Makefile

@@ -1262,11 +1262,15 @@ else
 	BLK_SHA1 = 1
 	OPENSSL_LIBSSL =
 endif
+ifdef NO_OPENSSL
+	LIB_4_CRYPTO =
+else
 ifdef NEEDS_SSL_WITH_CRYPTO
 	LIB_4_CRYPTO = $(OPENSSL_LINK) -lcrypto -lssl
 else
 	LIB_4_CRYPTO = $(OPENSSL_LINK) -lcrypto
 endif
+endif
 ifdef NEEDS_LIBICONV
 	ifdef ICONVDIR
 		BASIC_CFLAGS += -I$(ICONVDIR)/include