tools: add crc implementation

Add crc implementation, copied from the internal portable source,
adjusted to be c++ where relevant (e.g. using a vector, etc).

Change-Id: I0998342f4ec8843ba27bf554c2318ca9882e4f7a
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/tools/Makefile.am b/tools/Makefile.am
index acc6657..96feeb1 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -12,4 +12,5 @@
 	bt.cpp \
 	lpc.cpp \
 	blob_handler.cpp \
-	ipmi_handler.cpp
+	ipmi_handler.cpp \
+	crc.cpp