Determining if files X11/extensions/Xinerama.h exist failed with the following output:
Change Dir: /home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_3e73c/fast"
make[1]: Entering directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_3e73c.dir/build.make CMakeFiles/cmTC_3e73c.dir/build
make[2]: Entering directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_3e73c.dir/CheckIncludeFiles.c.o
/home/dawncrow/buildroot-test/scripts/instance-0/output/host/bin/arm-buildroot-linux-musleabihf-gcc --sysroot=/home/dawncrow/buildroot-test/scripts/instance-0/output/host/arm-buildroot-linux-musleabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2    -o CMakeFiles/cmTC_3e73c.dir/CheckIncludeFiles.c.o   -c /home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp/CheckIncludeFiles.c
/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp/CheckIncludeFiles.c:2:10: fatal error: X11/extensions/Xinerama.h: No such file or directory
 #include <X11/extensions/Xinerama.h>
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/cmTC_3e73c.dir/CheckIncludeFiles.c.o] Error 1
make[2]: Leaving directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
make[1]: *** [cmTC_3e73c/fast] Error 2
make[1]: Leaving directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'

Source:
/* */
#include <X11/extensions/Xinerama.h>


int main(void){return 0;}

Determining if the function XineramaQueryExtension exists in the Xinerama failed with the following output:
Change Dir: /home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_cfaf0/fast"
make[1]: Entering directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_cfaf0.dir/build.make CMakeFiles/cmTC_cfaf0.dir/build
make[2]: Entering directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_cfaf0.dir/CheckFunctionExists.c.o
/home/dawncrow/buildroot-test/scripts/instance-0/output/host/bin/arm-buildroot-linux-musleabihf-gcc --sysroot=/home/dawncrow/buildroot-test/scripts/instance-0/output/host/arm-buildroot-linux-musleabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCHECK_FUNCTION_EXISTS=XineramaQueryExtension   -o CMakeFiles/cmTC_cfaf0.dir/CheckFunctionExists.c.o   -c /home/dawncrow/buildroot-test/scripts/instance-0/output/host/share/cmake-3.8/Modules/CheckFunctionExists.c
Linking C executable cmTC_cfaf0
/home/dawncrow/buildroot-test/scripts/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_cfaf0.dir/link.txt --verbose=1
/home/dawncrow/buildroot-test/scripts/instance-0/output/host/bin/arm-buildroot-linux-musleabihf-gcc --sysroot=/home/dawncrow/buildroot-test/scripts/instance-0/output/host/arm-buildroot-linux-musleabihf/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCHECK_FUNCTION_EXISTS=XineramaQueryExtension    CMakeFiles/cmTC_cfaf0.dir/CheckFunctionExists.c.o  -o cmTC_cfaf0 -lXinerama 
/home/dawncrow/buildroot-test/scripts/instance-0/output/host/lib/gcc/arm-buildroot-linux-musleabihf/7.3.0/../../../../arm-buildroot-linux-musleabihf/bin/ld: cannot find -lXinerama
collect2: error: ld returned 1 exit status
make[2]: *** [cmTC_cfaf0] Error 1
make[2]: Leaving directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'
make[1]: *** [cmTC_cfaf0/fast] Error 2
make[1]: Leaving directory `/home/dawncrow/buildroot-test/scripts/instance-0/output/build/synergy-v2.0.12-beta/CMakeFiles/CMakeTmp'