I might need to do some hack around these "undefined" symbols, I'm pretty sure it might caused by the flags that's passed to ld.

Good luck, this is known as one of the most difficult packages and just so you are aware, if you succeed it's progress on #21130

I'll try to fix the undefined symbols problem first, then fix the Aarch64 build.

I tried to help, and I have noticed the following details:

• If the undefined symbols are ignored using TERMUX_PKG_UNDEF_SYMBOLS_FILES (they were probably always there and only detected after 56c04aa),
  • then the aarch64 build works at least similarly to how the package currently in the repository works (valgrind: /home/builder/.termux-build/valgrind/src/coregrind/m_redir.c:796 (void vgPlain_redir_add_ifunc_target(Addr, Addr)): Assertion 'old' failed. with valgrind ./a.out on a standard hello world built with no special build settings)
• On the other hand, https://android.googlesource.com/platform/bionic/+/439639268d1d7df90567102f51c540de37265538%5E%21/libc/bionic/bionic_elf_tls.cpp (a commit found in NDK r27) , appears as though it might be causing an effect in the 32-bit ARM build that presents similarly to a regression of [Bug]: Valgrind (vgdb): executable's TLS segment is underaligned #11224:
  • error: "valgrind": executable's TLS segment is underaligned: alignment is 32 (skew 8), needs to be at least 32 for ARM Bionic Aborted

Actually I don't think that valgrind built by clang will work properly anyway. It uses lots of hacks in gcc's compiler runtime (libgcc.a).

Well, in FreeBSD there is a package valgrind and Clang is the default compiler of FreeBSD, so I think the problems with this package might be specific to Android