Fix shell build on Solaris and cleanup Solaris SignalSender Run()

Fixes the build for the shell on illumos and Solaris. -D__C99FEATURES__ was added to mirror how the build is done on the normal platform. The changes in the platform code are a follow up to a prior review and has the Solaris implementation be more similar to the Linux version as opposed to the FreeBSD.

Contributed by Robert Mustacchi <rm@fingolfin.org>;

TEST=Note the test suite uncovered a bug in libm where pow(3M) was not doing the right thing on edge cases. The only test failures are related to this bug.

Committed: http://code.google.com/p/v8/source/detail?r=8502

[Mads Ager (chromium), 2011-07-01 05:47:17]

LGTM, thanks for bringing the solaris platform online again. :-)

I'll land.