Fix the import of tmp in smtsolver.ts

[cameel]

Looks like tmp is not being imported correctly. Not sure how that passed tests in #566 but tests are failing due to this in the main repo (ethereum/solidity#12583).

TypeError: Cannot read property 'fileSync' of undefined

In addition to merging this, we should really investigate why it passed our CI.

Steps to reproduce

git clone https://github.com/ethereum/solc-js/
cd solc-js/
npm install
npm run updateBinary
npm run test

# SMTCheckerWithSolver
# Simple test with axuiliaryInputRequested
ok 1108 should be truthy
/tmp/v0.1.1+commit.6ff4cd6.js:84
      throw ex;
      ^

TypeError: Cannot read property 'fileSync' of undefined
    at solve (/tmp/d/solc-js/dist/smtsolver.js:36:35)
    at Object.handleSMTQueries (/tmp/d/solc-js/dist/smtchecker.js:19:28)
    at Test.<anonymous> (/tmp/d/solc-js/dist/test/smtchecker.js:78:47)
    at Test.bound [as _cb] (/tmp/d/solc-js/node_modules/tape/lib/test.js:88:32)
    at Test.run (/tmp/d/solc-js/node_modules/tape/lib/test.js:105:10)
    at Test.bound [as run] (/tmp/d/solc-js/node_modules/tape/lib/test.js:88:32)
    at Test._end (/tmp/d/solc-js/node_modules/tape/lib/test.js:181:11)
    at Test.bound [as _end] (/tmp/d/solc-js/node_modules/tape/lib/test.js:88:32)
    at Immediate.<anonymous> (/tmp/d/solc-js/node_modules/tape/lib/test.js:127:18)
    at processImmediate (internal/timers.js:461:21)

[cameel]

/cc @stephensli

[cameel]

Haha, looks like we were bitten by #565 (comment) :P

# SMTCheckerWithSolver
# Simple test with axuiliaryInputRequested
ok 1105 Test requires z3. # SKIP

CI skips the test because of the missing Z3.

[stephen-slm]

LGTM - Good catch, being bitten by these tests are annoying. I would recommend if possible including z3 in the circleci installation. Allowing for these tests to be included.

[cameel]

Z3 is actually built into the binary and I was assuming CI uses that, which is why I let it through in the PR. Looks like I was wrong. We need to fix that. I'm going to create an issue so that we don't forget.