Bitcoin Master Branch breaks when trying compiling becouse of missing MinGW strnlen function #5338

Hi.

Bitcoin master branch compiliation breaks with this error Message here when trying to build it in Windows with MinGW.

protocol.cpp: In member function 'std::string CMessageHeader::GetCommand() const': protocol.cpp:43:81: error: 'strnlen' was not declared in this scope return std::string(pchCommand, pchCommand + strnlen(pchCommand, COMMAND_SIZE));

make[2]: *** [libbitcoin_common_a-protocol.o] Error 1 make[2]: Leaving directory /bitcoin/src' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory/bitcoin/src' make: *** [all-recursive] Error 1

Seems that strnlen is only spottily supported in mingw: http://sourceforge.net/p/mingw/bugs/1912/

Which is strange, as the mingw in gitian succeeds in building fine. Maybe some define is necessary...

I know the reason: we use mingw-w64 to build, which is a better-maintained fork of mingw

http://sourceforge.net/projects/mingw-w64/?source=directory