DonateSplitter compilation error
Having some compiling issues on manjaro, here is the output: 

```
Consolidate compiler generated dependencies of target xmrig-proxy
[  1%] Building CXX object CMakeFiles/xmrig-proxy.dir/src/proxy/splitters/donate/DonateSplitter.cpp.o
In file included from /home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.cpp:25:
/home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.h:60:17: error: ‘size_t’ has not been declared
   60 |     void remove(size_t id);
      |                 ^~~~~~
/home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.cpp:118:6: error: no declaration matches ‘void xmrig::DonateSplitter::remove(size_t)’
  118 | void xmrig::DonateSplitter::remove(size_t id)
      |      ^~~~~
In file included from /home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.cpp:25:
/home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.h:60:10: note: candidates are: ‘void xmrig::DonateSplitter::remove(int)’
   60 |     void remove(size_t id);
      |          ^~~~~~
/home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.cpp:107:6: note:                 ‘void xmrig::DonateSplitter::remove(xmrig::Miner*)’
  107 | void xmrig::DonateSplitter::remove(Miner *miner)
      |      ^~~~~
In file included from /home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.cpp:25:
/home/moore/test/xmrig-proxy/src/proxy/splitters/donate/DonateSplitter.h:46:7: note: ‘class xmrig::DonateSplitter’ defined here
   46 | class DonateSplitter : public IEventListener
      |       ^~~~~~~~~~~~~~
make[2]: *** [CMakeFiles/xmrig-proxy.dir/build.make:1364: CMakeFiles/xmrig-proxy.dir/src/proxy/splitters/donate/DonateSplitter.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/xmrig-proxy.dir/all] Error 2
```
