Fixed LAPACK support for OpenBLAS in Android.

[jadarve]

Patch to support LAPACK in Android as discussed in #402

These changes require to modify the Android NDK and replace the x86 and arm7 toolchains with those provided in https://github.com/buffer51/android-gfortran/releases

[saudet]

Thanks! Could you move the build instructions to the wiki page for that though?
https://github.com/bytedeco/javacpp-presets/wiki/Build-Environments#android-arm-and-x86

[jadarve]

I moved the instructions to the wiki page.

[saudet]

Thanks! Have you verified that all other presets also build fine with that installed? We'll need to confirm that...

[jadarve]

Oh, actually I have not verified if the other presets build with the modified toolchain. I will try and let you know.

[saudet]

We now have Travis CI working thanks to @vb216. Could you make those toolchain adjustments in the build script at https://github.com/bytedeco/javacpp-presets/blob/master/ci/install-travis.sh#L127 ? We'll then be able to see easily that everything builds fine with those changes and finally merge this! Thanks a lot

[saudet]

android-gfortran hasn't been updated in over a year now. Would you know of any alternative?

[jadarve]

I am not aware of any alternative.

[duanshanchong]

I have also encountered this problem. Have you solved it？

[saudet]

It looks like OpenBLAS no longer needs a Fortran compiler to build LAPACK, see pull OpenMathLib/OpenBLAS#3539.
Could you give that a try and update this pull request?

[saudet]

I've upgraded the presets for OpenBLAS 0.3.21 (see commit 7d9084f), which no longer requires a Fortran compiler to build LAPACK, so it's now available for all platforms, including Android, iOS, and Mac on ARM, so I think we can close this pull request. Please give it a try with the snapshots: http://bytedeco.org/builds/ Let me know if you encounter any issues with them though! Thank you