btop: [BUG] Build broken on Catalina and below: linking errors, unconditional usage of non-existing headers

Fails to build on Catalina and below: https://trac.macports.org/ticket/68871

On El Capitan down this fails (at least):

src/osx/sensors.cpp:22:10: fatal error: 'IOKit/hidsystem/IOHIDEventSystemClient.h' file not found
#include <IOKit/hidsystem/IOHIDEventSystemClient.h>
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/osx/sensors.cpp:22:10: note: did not find header 'hidsystem/IOHIDEventSystemClient.h' in framework 'IOKit' (loaded from '/System/Library/Frameworks')
1 warning and 1 error generated.
make: *** [obj/osx/sensors.o] Error 1

On Catalina through Sierra linking fails:

Linking and optimizing binary...
undef: __ZNSt3__120__libcpp_atomic_waitEPVKvx
undef: __ZNSt3__123__libcpp_atomic_monitorEPVKv
undef: __ZNSt3__123__cxx_atomic_notify_oneEPVKv
Undefined symbols for architecture x86_64:
  "std::__1::__libcpp_atomic_wait(void const volatile*, long long)", referenced from:
      Runner::_runner(void*) in lto.o
  "std::__1::__libcpp_atomic_monitor(void const volatile*)", referenced from:
      Runner::_runner(void*) in lto.o
  "std::__1::__cxx_atomic_notify_one(void const volatile*)", referenced from:
      Runner::run(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, bool, bool) in lto.o
      Runner::stop() in lto.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [btop] Error 1

I will test on PowerPC tomorrow, but expect the same headers errors at the very least.