Compare two different installations of symengine

[certik]

The issue #5 is for comparing two symengine branches, but we also need to compare the same symengine commit, but two different ways to install it, e.g.:

• with and without TCMALLOC
• with and without FLINT
• gcc 5.3 vs 7.0
• different docker base images, e.g. ubuntu 16.04 vs. alpine linux (the results can differ, due to gcc options about stack protection and different libc libraries)
  ...

So that we can determine how to get the fastest results for the given symengine commit.