Libreoffice android build error in linux arm64

i use the libreoffice branch distro/collabora/cp-6.4
and my computer is linux arm64 ubuntu 20.04

and my autogen.input

CC=/usr/bin/clang
CXX=/usr/bin/clang++

–with-jdk-home=/usr/lib/jvm/java-11-openjdk-arm64
–with-android-ndk=/home/$USER/Android/Sdk/ndk/android-ndk-r20b
–with-android-sdk=/home/$USER/Android/Sdk
–with-distro=CPAndroid
–enable-sal-log

i add
CC=/usr/bin/clang
CXX=/usr/bin/clang++
If I don’t add when run ./autogen.sh will report an error

but when i run make still error, i also try use ndk21, ndk23 all error too

error message here:
pixman-glyph.c:401:16: warning: unknown attribute ‘force_align_arg_pointer’ ignored [-Wunknown-attributes]
attribute((force_align_arg_pointer))
^
pixman-glyph.c:643:16: warning: unknown attribute ‘force_align_arg_pointer’ ignored [-Wunknown-attributes]
attribute((force_align_arg_pointer))
^
2 warnings generated.
CC pixman-region16.lo
CC pixman-region32.lo
CC pixman-solid-fill.lo
CC pixman-timer.lo
CC pixman-trap.lo
CC pixman-utils.lo
CCLD libpixman-1.la
…/libtool: line 1720: /home/chunhao/Android/Sdk/ndk/android-ndk-r20b/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ar: cannot execute binary file: Exec format error
make[4]: *** [Makefile:725: libpixman-1.la] Error 126
make[3]: *** [Makefile:503: all-recursive] Error 1
make[2]: *** [Makefile:410: all] Error 2
make[1]: *** [/home/chunhao/Desktop/octon/libreoffice/core/external/cairo/ExternalProject_pixman.mk:33: /home/chunhao/Desktop/octon/libreoffice/core/workdir/ExternalProject/pixman/build] Error 1
make: *** [Makefile:282: build] Error 2

In fact, I have successfully run it on an x86_64 computer, and I don’t need to add CC &
CXX settings, so I’m curious why it can’t run on an arm64 computer