Right! So there are just those 5 headers left. But ignoring them and building gives now indeed those linker errors:
1>CsoundFMOD.cpp
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(165,1): warning : control may reach end of non-void function [-Wreturn-type]
1>}
1>^
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(238,1): warning : control reaches end of non-void function [-Wreturn-type]
1>}
1>^
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(453,12): warning : ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
1> args[0] = "csound";
1> ^
1>3 warnings generated.
1>Tegra-Android/Debug/CsoundFMOD.o: In function `FMOD_Csound_dspprocess(FMOD_DSP_STATE*, unsigned int, FMOD_DSP_BUFFER_ARRAY const*, FMOD_DSP_BUFFER_ARRAY*, int, FMOD_DSP_PROCESS_OPERATION)':
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(550): undefined reference to `csoundGetMessageCnt'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(553): undefined reference to `csoundGetFirstMessage'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(554): undefined reference to `csoundPopFirstMessage'
1>Tegra-Android/Debug/CsoundFMOD.o: In function `FMOD_Csound_dspsetparamfloat(FMOD_DSP_STATE*, int, float)':
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(569): undefined reference to `csoundSetControlChannel'
1>Tegra-Android/Debug/CsoundFMOD.o: In function `FMOD_Csound_dspsetparamint(FMOD_DSP_STATE*, int, int)':
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(586): undefined reference to `csoundSetControlChannel'
1>Tegra-Android/Debug/CsoundFMOD.o: In function `FMODCsound::CompileCsound(std::__ndk1::basic_string<char, std::__ndk1::char_traits<char>, std::__ndk1::allocator<char> >)':
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(446): undefined reference to `csoundInitialize'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(448): undefined reference to `csoundCreate'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(449): undefined reference to `csoundCreateMessageBuffer'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(459): undefined reference to `csoundCompile'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(463): undefined reference to `csoundGetKsmps'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(464): undefined reference to `csoundPerformKsmps'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(465): undefined reference to `csoundGet0dBFS'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(466): undefined reference to `csoundGetSpin'
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(467): undefined reference to `csoundGetSpout'
1>Tegra-Android/Debug/CsoundFMOD.o: In function `FMODCsound::generate(float*, float*, unsigned int, int)':
1>C:\Users\User\source\repos\CsoundFMOD\CsoundFMOD\CsoundFMOD.cpp(489): undefined reference to `csoundPerformKsmps'
1>clang++.exe : error : linker command failed with exit code 1 (use -v to see invocation)