Replace os.popen() with subprocess.Popen. Based on patch by Victor Stinner.

If the "gcc", "cc" or "objdump" command is not available, the code was
supposed to raise an OSError exception. But there was a bug in the code. The
shell code returns the exit code 10 if the required command is missing, and the
code tries to check for the status 10. The problem is that os.popen() doesn't
return the exit code directly, but a status which should be processed by
os.WIFEXITED() and os.WEXITSTATUS(). In practice, the exception was never
raised. The OSError exception was not documented and ctypes.util.find_library()
is expected to return None if the library is not found.

Based on patch by Serhiy Storchaka.

Patch by Gareth Rees.

  exposed on the API which are not implemented on GNU/Hurd. They would not
  work at runtime anyway.

and recognizirable.

Update current tests that use old pattern with assertRaises
to make them more maintainable.

Patch by Demur Rumed.