BUILD: Added memory leak checks options for Valgrind

Signed-off-by: Gama <misept.dieseneuf@gmail.com>
GENERATORS: Generators now waiting for normalized frequency

As specified before generators are considered "dumb". In order to make
them the most generic possible, they will have their frequency setter
asking for normalized frequency.
This imply that hertz-to-cycles per sample conversion now have to be
done in VCOs.

Signed-off-by: Gama <misept.dieseneuf@gmail.com>