Make libnds detect no SD in the R4 when no FAT image is selected or fails to get created.

git-svn-id: https://svn.code.sf.net/p/desmume/code/trunk@4801 5577840e-afb3-4e59-9ef3-2b7f898b1952
Add a post_fakeboot hook for the mcrom_debug addon too.

git-svn-id: https://svn.code.sf.net/p/desmume/code/trunk@4802 5577840e-afb3-4e59-9ef3-2b7f898b1952