{,darwin64-}debug-test-64-clang Configure targets

These are based on debug-ben-debug-64-clang and is intended to produce
consistent settings for folks involved in the unit testing effort detailed at:

http://wiki.openssl.org/index.php/Unit_Testing

-fsanitize has been removed from the set of clang flags for now. Apparently
clang 3.1, which ships with FreeBSD 9.1, completely ignores -fsanitize. Clang
3.3, which ships with FreeBSD 9.2, compiles with it, but fails to link due to
the absence of libasan:

http://lists.freebsd.org/pipermail/freebsd-hackers/2013-December/043995.html
https://www.mail-archive.com/cfe-commits@cs.uiuc.edu/msg92260.html
http://reviews.llvm.org/D2644



We need -Wno-error=unused-const-variable because of this error:
.../crypto/ec/ec_lib.c:74:19: error: unused variable 'EC_version' [-Werror,-Wunused-const-variable]
static const char EC_version[] = "EC" OPENSSL_VERSION_PTEXT;

Change-Id: I2cba53537137186114c083049ea1233550a741f9
Signed-off-by: Mike Bland <mbland@acm.org>
Signed-off-by: Geoff Thorpe <geoff@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>