Fix: Revise the behavior under multiple PoW requests

[Fangop]

• The code has been formatted by gofmt
• This fix require 2 commits to fix 2 different mistakes.
• The test multiple PoW requests test is added.

Multiple PoW requests

The original C-GO interface will lead to errors under multiple PoW requests. The 2 reasons are below:

• Create and destroy dcurl for every PoW, which leads to error access of dcurl
• Uncertain length of return trytes These are fixed by 2 commit provided.

fix(C-GO): Remove redundat initializations

This commit fixed:

• Create and destroy dcurl for every PoW, which leads to error access of dcurl Change initialization to package init. Added an api for destroy dcurl

fix(C-GO): Align return trytes with length 2673

This commit fixed:

• Uncertain length of return trytes The return trytes of dcurl_entry have uncertain length(2673 or 2674). In C applications, dcurl will use init_trytes to make sure the length is 2673. However, using init_trytres may leads to memory leak in GO. Hence I use a length constraint for fixing this, as the implementation of init_trytres using memcpy.

feat(C-GO): Add mutiple PoW request test

This commit provide:

• A GO test for mutiple PoW request for SyncDcurlTest Using goroutine, this test can simulate mutiple PoW request. As the application of C-GO interface, this test verifies the usage of SyncDcurlProofOfWork. The SyncDcurlProofOfWork should return correct nonce under multiple requests.

[marktwtn]

Where are the corresponding initialization and destroy functions in cgo/pow/pow_test.go?

[marktwtn]

Fix commit message: Here is a test which simulates mutiple PoW request. mutiple -> multiple

[Fangop]

Fix commit message: Here is a test which simulates mutiple PoW request. mutiple -> multiple

Resolved

[marktwtn]

Fix commit message: Remove redundat initializations -> Remove redundant initializations Add multiple PoW request, simulates multiple PoW request -> PoW requests

[Fangop]

Fix commit message: Remove redundat initializations -> Remove redundant initializations Add multiple PoW request, simulates multiple PoW request -> PoW requests

Resolved?

[Fangop]

Rename the commit header feat(C-GO): Add multiple PoW requests test -> test(C-GO): Add multiple PoW requests test

Resolved. Also, I added DcurlDestroy at the last of pow package test.