Disable jemalloc on Android (fixes #636 and #642)

[fornwall]

Disabling jemalloc for Android fixes a build failure since jemalloc does not build out of the box for that platform on older API versions.

Android started using jemalloc as the system allocator around 2014 for most devices. In the latest Android version (11) the system allocator has been switched to Scudo, which while not being jemalloc is modern and actively maintained and should be used for most software on Android.

See:

• https://android-developers.googleblog.com/2020/06/system-hardening-in-android-11.html
• https://blog.nsogroup.com/a-tale-of-two-mallocs-on-android-libc-allocators-part-2-jemalloc/
• https://stackoverflow.com/questions/2266762/android-libc-version-and-malloc-implementation

[fornwall]

@sharkdp For CI builds of Android, would you be ok to start using GitHub CI for that? Personally I find it easier and more flexible to use that instead of Travis, and many projects have started going in that direction.

[sharkdp]

Thank you very much for your contribution!

@sharkdp For CI builds of Android, would you be ok to start using GitHub CI for that? Personally I find it easier and more flexible to use that instead of Travis, and many projects have started going in that direction.

Indeed. We have already switched my bat and pastel projects to GitHub Actions. If we start to use GitHub Actions, I'd like to move to it completely (and disable Travis and Appveyor). This would also mean that we have to port the whole deployment code to GitHub Actions.

I'll probably not work on this myself, but I would definitely be in favor of this change. The PR on the bat repository would probably be a good resource, as the CI system is quite similar:

sharkdp/bat#1023 and sharkdp/bat#1121

[sharkdp]

fix released in v8.2.0.