Makefile alphabet.cpp

[xusailor]

In order to support the arm platform，the above code has been added.

[junaruga]

I faced this alphabet.cpp's error that prevents bowtie to be built with Fedora, gcc 10 & CPU architectures: aarch64 (arm64), s390x, ppc64le.

The -Wnarrowing is actually a build error on the environments.

alphabet.cpp:293:1: error: narrowing conversion of ‘-1’ from ‘int’ to ‘char’ inside { } [-Wnarrowing]

This is a backport from bowtie2 commit: BenLangmead/bowtie2@c619b9a .

And we need to fix alphabet.h too.

[junaruga]

Note: I sent PR to enable aarch64, s390x, ppc64le #102 .

[ch4rr0]

Thanks for submitting this pull request, Jun. We already made a similar change to the codebase in the bug_fixes branch. Feel free to check out the changes we have on there.

[junaruga]

Thanks for the fixing!
@xusailor you can close this PR. This PR was merged as the commit: 8a6d6ca . You can also try to use the released bowtie 1.3.0 aarch64 (arm64) binary.