msvc: use OpenSSL's SHA-1 routines

Just like 1e2ce1d (sha1: Use OpenSSL SHA1 routines on MINGW, 2016-10-12),
we now use OpenSSL's SHA-1 routines instead of Git's own because OpenSSL
is substantially faster as of version 1.0.2: it now uses hardware
acceleration on Intel processors much more effectively.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: jeffhostetler

config.mak.uname

@@ -381,7 +381,6 @@ ifeq ($(uname_S),Windows)
 	NO_REGEX = YesPlease
 	NO_GETTEXT = YesPlease
 	NO_PYTHON = YesPlease
-	BLK_SHA1 = YesPlease
 	ETAGS_TARGET = ETAGS
 	NO_INET_PTON = YesPlease
 	NO_INET_NTOP = YesPlease