Missing include in Algorithms/bet/math/savgol.cpp

With gcc 7.3.0 from psi modules on linux I get the compiler error:

src/Algorithms/bet/math/savgol.cpp:406:5: error: ‘memcpy’ was not declared in this scope
     memcpy(&cIn[1], c, sizeof(double)*n);
     ^~~~~~
/home/scratch/OPAL/OPAL-fork/OPAL-src/src/Algorithms/bet/math/savgol.cpp:406:5: note: suggested alternative: ‘wmemcpy’
     memcpy(&cIn[1], c, sizeof(double)*n);
     ^~~~~~
     wmemcpy

This is due to a missing include <cstring>.