feat(redox): dynamic linking

Required for the upcoming dynamic linking patches for cookbook.

• Revert "gcc/config/redox.h: default executables to static".

I am not entirely sure if this revert breaks any existing package (for what package was this required?) that is currently statically compiled. In the prescript of cookbook, --static is automatically added to LD_FLAGS and --disable-shared --enable-static is automatically passed if building with cookbook_configure; which should be sufficient. It did not break anything with the minimal build config.

• Enable rdynamic driver option.