Fixed Android missing pthread_setcancelstate and pthread_cancel

[sheldonrobinson]

Using SomeDevHere/libbthread to add missing pthread_setcancelstate and pthread_cancel.

1. Check for Android and include bthread.h in H5private.h
2. Add link library libcancelthread.so

[derobins]

I'd be happy to approve this, but since we have no Android testing, it'd immediately become dead code. Can you add a GitHub action to build/test on Android?

[hyoklee]

Hi, @sheldonrobinson !

Thank you so much for your patch to support bthread on Android!

However, I think your PR doesn't work if bthread is not present on system:

MakeCommand:/usr/local/bin/cmake --build . --config "${CTEST_CONFIGURATION_TYPE}"
Run command: "/usr/local/bin/cmake" "--build" "." "--config" "Release"
[  0%] Building C object src/CMakeFiles/hdf5-static.dir/H5.c.o
In file included from /home/runner/work/actions/actions/src/H5.c:21:
/home/runner/work/actions/actions/src/H5private.h:68:10: fatal error: 'bthread.h' file not found
   68 | #include <bthread.h>
      |          ^~~~~~~~~~~
1 error generated.
gmake[2]: *** [src/CMakeFiles/hdf5-static.dir/build.make:76: src/CMakeFiles/hdf5-static.dir/H5.c.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:2099: src/CMakeFiles/hdf5-static.dir/all] Error 2
gmake: *** [Makefile:166: all] Error 2
Command exited with the value: 2
MakeCommand:/usr/local/bin/cmake --build . --config "${CTEST_CONFIGURATION_TYPE}"
Error(s) when building project
   3 Compiler errors
   1 Compiler warnings

Would you please improve your PR to fix the above issue?

[hyoklee]

For CMake users, this PR requires
https://github.com/sheldonrobinson/libbthread

Once libbthread is installed properly with either autotools or cmake,
NDK can build HDF5 successfully.

[sheldonrobinson]

I looked at hdf5 Github workflows and it seems we are not currently building/testing for Android. We can proceed in either of the following ways:

1. Merge PR given that it does not break or interfere with current builds.
   1. Cons The caveat, user needs to install SomeDevHere/libbthread where I also submitted PR to fix pthread link error and don't want to fork libbthread codebase.
   2. Pros Quick and easy
2. Add Android target build/test Github workflow.
   1. Cons Will take longer, also waiting on upstream fix to SomeDevHere/libbthread.
   2. Pros This is what needs to occur in the end.

[derobins]

Without testing, this code will quickly break as we move things around. We had this problem with MinGW and Cygwin before we integrated them into our CI. People would submit patches, everything would be fine for a version or two, we'd make changes, and then everything would be broken again.