Adding Crunch at r319.

third_party/crunch/crnlib/crn_checksum.h

@@ -0,0 +1,13 @@
+// File: crn_checksum.h
+#pragma once
+
+namespace crnlib
+{
+   const uint cInitAdler32 = 1U;
+   uint adler32(const void* pBuf, size_t buflen, uint adler32 = cInitAdler32);
+   
+   // crc16() intended for small buffers - doesn't use an acceleration table.
+   const uint cInitCRC16 = 0;
+   uint16 crc16(const void* pBuf, size_t len, uint16 crc = cInitCRC16);
+   
+}  // namespace crnlib