Fixing "configure: error: ACC conformance test failed. Stop." when building ucl on macos with M1 (arm64) CPU

gistfile1.txt

git clone git@github.com:Distrotech/ucl.git
cd ucl
./configure CFLAGS="$CFLAGS -Wno-error=implicit-function-declaration"
make -j 10
sudo make install

If you need ucl to build UPX, make sure you execute this right before calling the UPX Makefile

From UPX's source folder:

UPX_UCLDIR=/path/to/src/ucl
make -j 10
...
-Wshadow -Wvla -Wwrite-strings -Werror -o work.o -c work.cpp
g++ -std=c++14 -O2 -fno-delete-null-pointer-checks -fno-strict-aliasing -fno-strict-overflow -funsigned-char -fstack-protector-strong -Wall -Wextra -Wcast-align -Wcast-qual -Wmissing-declarations -Wpointer-arith -Wshadow -Wvla -Wwrite-strings -Werror -o upx.out c_file.o c_init.o c_none.o c_screen.o compress.o compress_lzma.o compress_ucl.o compress_zlib.o except.o file.o filter.o filteri.o help.o lefile.o linker.o main.o mem.o msg.o p_armpe.o p_com.o p_djgpp2.o p_exe.o p_lx_elf.o p_lx_exc.o p_lx_interp.o p_lx_sh.o p_mach.o p_ps1.o p_sys.o p_tmt.o p_tos.o p_unix.o p_vmlinx.o p_vmlinz.o p_w32pe.o p_w64pep.o p_wcle.o packer.o packer_c.o packer_f.o packhead.o packmast.o pefile.o s_djgpp2.o s_object.o s_vcsa.o s_win32.o snprintf.o ui.o util.o work.o -L/Users/gubatron/workspace/ucl/src/.libs/ -lucl -lz
make -C doc all
make[1]: Nothing to be done for `all'.

The executable will be inside src/ as upx.out