sha1dc: do not use standard includes

The updated SHA1DC library allows us to use custom includes instead of
using standard includes. Due to requirements with cross-platform, we
provide some custom system includes files like for example the
"stdint.h" file on Win32. Because of this, we want to make sure to avoid
breaking cross-platform compatibility when SHA1DC is enabled.

To use the new mechanism, we can simply define
`SHA1DC_NO_STANDARD_INCLUDES`. Furthermore, we can specify custom
include files via two defines, which we now use to include our
"common.h" header.

CMakeLists.txt

@@ -296,6 +296,9 @@ ENDIF()
 # Specify sha1 implementation
 IF (USE_SHA1DC)
 	ADD_DEFINITIONS(-DGIT_SHA1_COLLISIONDETECT)
+	ADD_DEFINITIONS(-DSHA1DC_NO_STANDARD_INCLUDES=1)
+	ADD_DEFINITIONS(-DSHA1DC_CUSTOM_INCLUDE_SHA1_C=\"common.h\")
+	ADD_DEFINITIONS(-DSHA1DC_CUSTOM_INCLUDE_UBC_CHECK_C=\"common.h\")
 	FILE(GLOB SRC_SHA1 src/hash/hash_collisiondetect.c src/hash/sha1dc/*)
 ELSEIF (WIN32 AND NOT MINGW)
 	ADD_DEFINITIONS(-DGIT_SHA1_WIN32)