test: fix test/test-configure-python on AIX
test: fix test/test-configure-python on AIX

On AIX, lib/configure.js attempts to locate node.exp via calls to
fs.openSync() and fs.closeSync(). Add these functions to the mocked
`graceful-fs` object in test/test-configure-python.js.

PR-URL: https://github.com/nodejs/node-gyp/pull/1131
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: Gibson Fahnestock <c0a850ada395a21aea35ea96f1fadcdd1d6eb48b@gmail.com>
Reviewed-By: Michael Dawson <241bf52ebd97cc4ec83d57b04d1f9e9053df032e@ca.ibm.com>

isaacs/node-gyp,nodejs/node-gyp,TooTallNate/node-gyp,nodegit/node-gyp,nodejs/node-gyp,nwjs/nw-gyp,TooTallNate/node-gyp,nodejs/node-gyp,isaacs/node-gyp,nwjs/nw-gyp,nodejs/node-gyp,isaacs/node-gyp,isaacs/node-gyp,saper/node-gyp,refack/node-gyp,refack/node-gyp,nodegit/node-gyp,nwjs/nw-gyp,saper/node-gyp,nwjs/nw-gyp,refack/node-gyp,isaacs/node-gyp,nwjs/nw-gyp,saper/node-gyp,saper/node-gyp,nodegit/node-gyp,refack/node-gyp,TooTallNate/node-gyp,nodegit/node-gyp,nodejs/node-gyp,saper/node-gyp,TooTallNate/node-gyp,refack/node-gyp,TooTallNate/node-gyp,nodegit/node-gyp