So when compiling the newest release (also happens on git master) I get this:

[ 45%] Linking CXX executable approx1_cpu
../src/backend/cpu/libafcpu.so.3.2.0: undefined reference to `af_save_image_memory'

Using gcc 5.2.

make verbose=1 output is:

[ 45%] Linking CXX executable approx1_cpu
cd /home/svenstaro/src/arrayfire/build/test && /usr/bin/cmake -E cmake_link_script    CMakeFiles/approx1_cpu.dir/link.txt --verbose=1
/usr/bin/c++   -O3 -DNDEBUG   CMakeFiles/approx1_cpu.dir/approx1.cpp.o  -o approx1_cpu -rdynamic ../src/backend/cpu/libafcpu.so.3.2.0 -pthread ../third_party/gtest/src/googletest-build/./libgtest.a   ../third_party/gtest/src/googletest-build/./libgtest_main.a -Wl,- rpath,/home/svenstaro/src/arrayfire/build/src/backend/cpu:/home/svenstaro/src/arrayfire/build/third_party/ forge/src/forge-ext-build/src -Wl,-rpath-link,/home/svenstaro/src/arrayfire/build/third_party/forge/src/forge- ext-build/src