So it couldn't find an include file (linux/limits.h) which I solved by installing linux-3.16.y_api_headers.
But now the build fails:
$ sudo make install
if g++ -DHAVE_CONFIG_H -I. -I. -I. -g -O2 -MT btcontent.o -MD -MP -MF ".deps/btcontent.Tpo" -c -o btcontent.o btcontent.cpp; \
then mv -f ".deps/btcontent.Tpo" ".deps/btcontent.Po"; else rm -f ".deps/btcontent.Tpo"; exit 1; fi
btcontent.cpp: In function 'void Sha1(char*, size_t, unsigned char*)':
btcontent.cpp:70:3: error: 'SHA_CTX' was not declared in this scope
SHA_CTX context;
^
btcontent.cpp:71:14: error: 'context' was not declared in this scope
SHA1_Init(&context);
^
btcontent.cpp:71:21: error: 'SHA1_Init' was not declared in this scope
SHA1_Init(&context);
^
btcontent.cpp:72:47: error: 'SHA1_Update' was not declared in this scope
SHA1_Update(&context,(unsigned char*)ptr,len);
^
btcontent.cpp:73:25: error: 'SHA1_Final' was not declared in this scope
SHA1_Final(dm,&context);
^
Makefile:301: recipe for target 'btcontent.o' failed
make: *** [btcontent.o] Error 1
$
I have sent a message to the developers for help.