COMPLEX_FLOAT bugs

[Paul Henning]

The gcc tests:
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O0 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O1 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O2 
FAIL: gcc.c-torture/execute/complex-5.c execution,  -O2 -fomit-frame-pointer -finline-functions 

have consistantly failed for me under mips-sgi-irix6.3, so I thought I
would take a look at it.  It seems that the big problems involve
register allocation when passing and returning complex floats.
To make the assembly a little easier, I got rid of the assignment to
"y" contained in the original test, yielding