Determining if the function dlopen exists in the dl failed with the following output:
Change Dir: /home/buildroot/autobuild/instance-3/output-1/build/libuhttpd-3.8.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_f6692/fast && make[1]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/libuhttpd-3.8.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_f6692.dir/build.make CMakeFiles/cmTC_f6692.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/libuhttpd-3.8.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_f6692.dir/CheckFunctionExists.c.o
/home/buildroot/autobuild/instance-3/output-1/host/bin/arm-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/arm-buildroot-uclinux-uclibcgnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -Wl,-elf2flt -static -DCHECK_FUNCTION_EXISTS=dlopen  -DNDEBUG   -o CMakeFiles/cmTC_f6692.dir/CheckFunctionExists.c.o   -c /home/buildroot/autobuild/instance-3/output-1/host/share/cmake-3.15/Modules/CheckFunctionExists.c
Linking C executable cmTC_f6692
/home/buildroot/autobuild/instance-3/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_f6692.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-3/output-1/host/bin/arm-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/arm-buildroot-uclinux-uclibcgnueabi/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -Wl,-elf2flt -static -DCHECK_FUNCTION_EXISTS=dlopen  -DNDEBUG  -Wl,-elf2flt -static  CMakeFiles/cmTC_f6692.dir/CheckFunctionExists.c.o  -o cmTC_f6692 -ldl 
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/arm-buildroot-uclinux-uclibcgnueabi/bin/ld.real: CMakeFiles/cmTC_f6692.dir/CheckFunctionExists.c.o: in function `main':
CheckFunctionExists.c:(.text.startup+0x6): undefined reference to `dlopen'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_f6692.dir/build.make:86: recipe for target 'cmTC_f6692' failed
make[2]: *** [cmTC_f6692] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/libuhttpd-3.8.0/CMakeFiles/CMakeTmp'
Makefile:121: recipe for target 'cmTC_f6692/fast' failed
make[1]: *** [cmTC_f6692/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/libuhttpd-3.8.0/CMakeFiles/CMakeTmp'