The compiler was interpreting 'Q' as an exponent letter in a literal
real constant as meaning real(kind=10) on x86-64, which is the legacy
80387 80-bit extended precision floating-point type. It turns out that
'Q' means kind=16 with all other compilers, even for x86-64 targets.
Change to conform.
Implement the UNSIGNED extension type and operations under control of a
language feature flag (-funsigned).
This is nearly identical to the UNSIGNED feature that has been available
in Sun Fortran for years, and now implemented in GNU Fortran for
gfortran 15, and proposed for ISO standardization in J3/24-116.txt.
See the new documentation for details; but in short, this is C's
unsigned type, with guaranteed modular arithmetic for +, -, and *, and
the related transformational intrinsic functions SUM & al.
