PolarSSL: update to current stable version (1.3.4)
PolarSSL: delete unused files
PolarSSL: strip down CMakeLists.txt
PolarSSL: adapt to the PolarSSL 1.3 API
PolarSSL: use entropy interface instead of havege

PolarSSL 1.3 has disabled HAVEGE by default (because it is "considered
unsafe for primary usage") and at least Debian is following that
setting.
PolarSSL: add VS2013 .vcxproj file back
PolarSSL: add new .c files to .vcxproj file