Added travisCI SIMDe example for arm64 + fix to Makefile for SIMDe

[mbrcic]

Reproductive command steps for arm64 minimap2 using SIMDe, as asked in: https://github.com/lh3/minimap2/pull/597

In process, I have fixed an error in Makefile.simde that probably appeared during the merge of previous PR.

[junaruga]

Thanks! awesome! Let's wait @lh3 's response.

[mbrcic]

With this syntax mistake fixed, travisCI should do 7 tests, twice on arm64.

[junaruga]

I think it's better to unify this PR's 2 commits to 1 commit by doing squash. (such as git rebase -i <commit hash>).