Apply UB constraints only on the relevant Phi branches

This patch fixes the unsoundness issue #13.
Add souper-check tool

This tool is based on souperweb-backend.cpp, but it's
intended to be run from the command line.
Merge pull request #60 from rsas/souper-check2

Add souper-check tool
Skip phis with one operand (issue #61)
extract value support

TODO - yet to figure out handling of aggregates
Merge pull request #64 from rsas/issue61

Skip phis with one operand (issue #61)
bump Klee version

bump LLVM version

bump Hiredis version

install the Hiredis static library and include files by hand; do not build the
shared lib
Merge pull request #69 from regehr/bump-klee

bump Klee version, LLVM version, Hiredis version, build and install only the static hiredis lib
Merge remote-tracking branch 'upstream/master' into extract-insert
pseudo code for extract value