Calls like `debug("something\n", 0, 0, 0, 0)` cause clang warnings,
because debug() is a macro that passes its arguments to printf(), and
clang warns about extra 0s to printf(). Silence the warnings by
hiding the printf() in a new function do_debug(). The code still
passes extra 0s to printf(), but clang can't warn.
Macros debug() and verbose() should use C99 __VA_ARGS__, so they don't
require the extra 0s; but ACK doesn't use __VA_ARGS__ yet.
Adjust some format strings for debug() or fatal(), or cast their
arguments, to match their types. I don't know whether uint32_t is
unsigned int or unsigned long, so I cast it to unsigned long, and
print it with "%lx".
In util/led/sym.c, #include "save.h" to declare savechar(), and use
parentheses to silence a clang warning in hash().
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