mesa/get: Make GetFloat/GetDouble of TYPE_INT_N not normalize things.

mesa/get: Make GetFloat/GetDouble of TYPE_INT_N not normalize things.

GetFloat of integer valued things is supposed to perform a simple
int -> float conversion.  INT_TO_FLOAT is not that.  Instead, it
converts [-2147483648, 2147483647] to a normalized [-1.0, 1.0] float.

This is only used for COMPRESSED_TEXTURE_FORMATS, which nobody in
their right mind would try and access via glGetFloat(), but we may
as well fix it.

Found by inspection.

v2: Gotta catch 'em all (fix another case of this caught by Ilia)

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>