Revert "Get rid of libssh2 embedding"

The embedding was removed as a libssh2 release with Windows crypto
support became available, but dependencies are still annoying so this
ahs been requested again.

This reverts commit 20dcb731.

CMakeLists.txt

@@ -59,6 +59,10 @@ IF(MSVC)
 	# are linking statically
 	OPTION( STATIC_CRT		"Link the static CRT libraries"	ON  )
 
+	# If you want to embed a copy of libssh2 into libgit2, pass a
+	# path to libssh2
+	OPTION( EMBED_SSH_PATH		"Path to libssh2 to embed (Windows)" OFF )
+
 	ADD_DEFINITIONS(-D_SCL_SECURE_NO_WARNINGS)
 	ADD_DEFINITIONS(-D_CRT_SECURE_NO_DEPRECATE)
 	ADD_DEFINITIONS(-D_CRT_NONSTDC_NO_DEPRECATE)
@@ -172,6 +176,13 @@ IF (COREFOUNDATION_FOUND)
 ENDIF()
 
 
+IF (WIN32 AND EMBED_SSH_PATH)
+	FILE(GLOB SRC_SSH "${EMBED_SSH_PATH}/src/*.c")
+	INCLUDE_DIRECTORIES("${EMBED_SSH_PATH}/include")
+	FILE(WRITE "${EMBED_SSH_PATH}/src/libssh2_config.h" "#define HAVE_WINCNG\n#define LIBSSH2_WINCNG\n#include \"../win32/libssh2_config.h\"")
+	ADD_DEFINITIONS(-DGIT_SSH)
+ENDIF()
+
 IF (WIN32 AND WINHTTP)
 	ADD_DEFINITIONS(-DGIT_WINHTTP)
 	INCLUDE_DIRECTORIES(deps/http-parser)
@@ -501,7 +512,7 @@ ELSE()
 ENDIF()
 
 # Compile and link libgit2
-ADD_LIBRARY(git2 ${SRC_H} ${SRC_GIT2} ${SRC_OS} ${SRC_ZLIB} ${SRC_HTTP} ${SRC_REGEX} ${SRC_SHA1} ${WIN_RC})
+ADD_LIBRARY(git2 ${SRC_H} ${SRC_GIT2} ${SRC_OS} ${SRC_ZLIB} ${SRC_HTTP} ${SRC_REGEX} ${SRC_SSH} ${SRC_SHA1} ${WIN_RC})
 TARGET_LINK_LIBRARIES(git2 ${SECURITY_DIRS})
 TARGET_LINK_LIBRARIES(git2 ${COREFOUNDATION_DIRS})
 TARGET_LINK_LIBRARIES(git2 ${SSL_LIBRARIES})
@@ -571,7 +582,7 @@ IF (BUILD_CLAR)
 		${CLAR_PATH}/clar.c
 		PROPERTIES OBJECT_DEPENDS ${CLAR_PATH}/clar.suite)
 
-	ADD_EXECUTABLE(libgit2_clar ${SRC_H} ${SRC_GIT2} ${SRC_OS} ${SRC_CLAR} ${SRC_TEST} ${SRC_ZLIB} ${SRC_HTTP} ${SRC_REGEX} ${SRC_SHA1})
+	ADD_EXECUTABLE(libgit2_clar ${SRC_H} ${SRC_GIT2} ${SRC_OS} ${SRC_CLAR} ${SRC_TEST} ${SRC_ZLIB} ${SRC_HTTP} ${SRC_REGEX} ${SRC_SSH} ${SRC_SHA1})
 
 	TARGET_LINK_LIBRARIES(libgit2_clar ${COREFOUNDATION_DIRS})
 	TARGET_LINK_LIBRARIES(libgit2_clar ${SECURITY_DIRS})