Fix pinv tests for 32-bit configurations

pinv test causes a test failure on 32-bit configurations:

```
    From worker 2:       * linalg/pinv
exception on 2: ERROR: mismatch of non-finite elements: 
  vecnorm(a * apinv * a - a) / vecnorm(a) = NaN
  0 = 0
while loading linalg/pinv.jl, in expression starting on line 106
ERROR: mismatch of non-finite elements: 
  vecnorm(a * apinv * a - a) / vecnorm(a) = NaN
  0 = 0
while loading linalg/pinv.jl, in expression starting on line 106
while loading C:\projects\julia\test\runtests.jl, in expression starting on line 42
```

In forming testing matrices, integer expression i^5 overflows on 32-bit machines, replace i^5 with float(i)^5.

Also, removed calls to randn(m,n) (replacing with deterministic hilb(m,n)) while creating a test matrix to prevent nasty surprises in the future should randn change for some reason,