sys_indirect()

I suspect that the only way to `migrate' libcs would be a big bang with 
interface back-compatibility (which is, of course, exactly how glibc 
upgrades work). Nothing else works because of the presence of critical 
global data structures whose format must be understood by everything that 
accesses them (I'm thinking mostly of malloc() and free() here, but the 
exception unwinder is another example, which is why libgcc_s.so exists at 
all as opposed to just libgcc.a).