Fix the problems exposed by the callingconv1.d test case. The first was that unless otherwise specified, inputs are assumed to be in registers even if they specify a "matching output" that's in memory. While testing that fix, I also ran into a bug causing the generated "matching output" for any input was always the first one instead of the correct one.

[Environment]

DFLAGS=-I%@P%/../lphobos -I%@P%/../import -L-L%@P%/../lib
# -R%@P%/../lib