[PATCH 2/3] sha1dc: use sha1collisiondetection as a submodule

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Replace the forked sha1dc directory with a copy of the upstream code
imported as a submodule. This is the exact same code as now exists in
the sha1dc/ directory.

The initial reason for copy/pasting the code into sha1dc and locally
modifying it was that it needed to be altered to work with the git
project.

The upstream project has accepted my code changes to allow us to use
their code as-is, see the preceding commit for details. So import the
code as a submodule instead, this will make it easier to keep
up-to-date with any upstream fixes or improvements.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 .gitmodules            | 4 ++++
 Makefile               | 4 ++--
 hash.h                 | 2 +-
 sha1collisiondetection | 1 +
 4 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 .gitmodules
 create mode 160000 sha1collisiondetection

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000..cbeebdab7a
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "sha1collisiondetection"]
+	path = sha1collisiondetection
+	url = https://github.com/cr-marcstevens/sha1collisiondetection.git
+	branch = master
diff --git a/Makefile b/Makefile
index ffa6da71b7..d7f506e790 100644
--- a/Makefile
+++ b/Makefile
@@ -1412,8 +1412,8 @@ ifdef APPLE_COMMON_CRYPTO
 	BASIC_CFLAGS += -DSHA1_APPLE
 else
 	DC_SHA1 := YesPlease
-	LIB_OBJS += sha1dc/sha1.o
-	LIB_OBJS += sha1dc/ubc_check.o
+	LIB_OBJS += sha1collisiondetection/lib/sha1.o
+	LIB_OBJS += sha1collisiondetection/lib/ubc_check.o
 	BASIC_CFLAGS += \
 		-DSHA1_DC \
 		-DSHA1DC_NO_STANDARD_INCLUDES \
diff --git a/hash.h b/hash.h
index a11fc9233f..9d9892ac3e 100644
--- a/hash.h
+++ b/hash.h
@@ -8,7 +8,7 @@
 #elif defined(SHA1_OPENSSL)
 #include <openssl/sha.h>
 #elif defined(SHA1_DC)
-#include "sha1dc/sha1.h"
+#include "sha1collisiondetection/lib/sha1.h"
 #else /* SHA1_BLK */
 #include "block-sha1/sha1.h"
 #endif
diff --git a/sha1collisiondetection b/sha1collisiondetection
new file mode 160000
index 0000000000..b45fcefc71
--- /dev/null
+++ b/sha1collisiondetection
@@ -0,0 +1 @@
+Subproject commit b45fcefc71270d9a159028c22e6d36c3817da188
-- 
2.13.0.303.g4ebf302169