Convert char** se parameters to CONST (break with C standard

[phillipjohnston]

There's lots of const casting around:

	if (se)
		*se = (char*)s;

This generates a warning, and I am happy:

[60/63] Compiling C object 'src/src@@@c_native@sta/gdtoa_src_strtodg.c.o'.
../src/gdtoa/src/strtodg.c:1016:16: warning: cast from 'const char *' to 'char *' drops const qualifier [-Wcast-qual]
                *se = (char*)s;

The standard doesn't specify this argument as a const char *, even though we pass in a const char string. Most implementations cast away const.

So I want to make a better version of the libc headers which keeps this const. You can cast it away on your own time if you need to.

[phillipjohnston]

The signature to look for is:

	if (se)
		*se = (char*)(uintptr_t)s;

I am sad that I had to do it.