- Eliminate provably non-pointer nodes from graphs.

This helps a lot of testcases, for example:
            New Time  New #Nodes     Old Time    Old #Nodes
254.gap:    91.1024     21605        91.1397     22657
povray31:    2.7807      8613         3.0152     10338
255.vortex:  1.2034      8153         1.2172     8822
moria:        .6756      3150          .7054     3877
300.twolf:    .1652      2010          .1851     3270

Typically, testcases which use long and ulong integers a lot get better, f.e. povray above.

llvm-svn: 5566