librav1e: error while loading shared library libc.so: invalid ELF header

I'm trying to use precompiled binaries of librav1e: https://github.com/xiph/rav1e/releases/tag/v0.6.6

More precisely, I'm using librav1e-0.6.6-linux-aarch64.tar.gz (also tried weekly build with the same result) on Ubuntu 18.04.

When I'm trying to compile another library which is depends on librav1e:

[ 84%] Linking CXX executable heif-test
/usr/bin/ld: warning: libc.so, needed by //usr/local/lib/librav1e.so.0, not found (try using -rpath or -rpath-link)
/usr/local/lib/librav1e.so.0: undefined reference to `fstat64'
/usr/local/lib/librav1e.so.0: undefined reference to `stat64'
collect2: error: ld returned 1 exit status

Inspecting .so file:

# tar xvf librav1e-linux-aarch64.tar.gz 
include/
include/rav1e/
include/rav1e/rav1e.h
lib/
lib/librav1e.a
lib/librav1e.so
lib/librav1e.so.0.6.1
lib/librav1e.so.0
lib/pkgconfig/
lib/pkgconfig/rav1e.pc

# ldd ./lib/librav1e.so
./lib/librav1e.so: error while loading shared libraries: /usr/lib/aarch64-linux-gnu/libc.so: invalid ELF header

# dpkg -S libc.so
libc6-dev:arm64: /usr/lib/aarch64-linux-gnu/libc.so
libc6:arm64: /lib/aarch64-linux-gnu/libc.so.6

# cat /usr/lib/aarch64-linux-gnu/libc.so
/* GNU ld script
   Use the shared library, but some functions are only in
   the static library, so try that secondarily.  */
OUTPUT_FORMAT(elf64-littleaarch64)
GROUP ( /lib/aarch64-linux-gnu/libc.so.6 /usr/lib/aarch64-linux-gnu/libc_nonshared.a  AS_NEEDED ( /lib/aarch64-linux-gnu/ld-linux-aarch64.so.1 ) )

# rm /usr/lib/aarch64-linux-gnu/libc.so
# ldd ./lib/librav1e.so
    linux-vdso.so.1 (0x0000ffff95b61000)
    libgcc_s.so.1 => /lib/aarch64-linux-gnu/libgcc_s.so.1 (0x0000ffff9590d000)
    libc.so => not found
    libc.so.6 => /lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff957b4000)
    /lib/ld-linux-aarch64.so.1 (0x0000ffff95b35000)

So it looks like there two shared versions of libc.so in librav1e.so and one of them is GNU ld script in my system. Is this ok? What can I do with errors?

The package you're using is not correctly linked. On Linux, every shared library installed for public use has an SONAME, which specifies the shared library path. This value should contain the unqualified name, which should be in the form libfoo.so.N, where foo is the shared library name, and N is the ABI version. Different values of N result in incompatible libraries.

It isn't acceptable to link libraries directly against a name such as libc.so, since that doesn't contain an ABI version. Now, it is extremely unlikely that glibc will change its ABI version, but in the past, there were different versions of libc, and you would not want to link a program using glibc 2 (libc.so.6) with a program using libc5 (libc.so.5). Libraries that are correctly compiled for public use will not link against libc in this way.

You should not delete /usr/lib/aarch64-linux-gnu/libc.so (and you should re-install the package providing it if you have), and either compile the shared library yourself or report the problem to the maintainer.

Note that newer versions of Debian and Ubuntu ship this package, so you may find that it's helpful to download that source package and build it, modifying as necessary, which will build it in a way that works with your OS. That may, however, be made more difficult by the fact that Ubuntu 18.04 is no longer receiving regular updates, security or otherwise.