[cppcheck] Don't use --project together with source files

```
cppcheck: error: --project cannot be used in conjunction with source files.
```

Author: netromdk

CMakeLists.txt

@@ -129,8 +129,7 @@ if (found_cppcheck)
 
     # unusedFunction can't be used with -j for some reason.
     cppcheck --enable=all -j ${CPU_COUNT} --std=c++17 --language=c++ --inconclusive
-             --project=${CMAKE_CURRENT_BINARY_DIR}/compile_commands.json
-             ${CMAKE_SOURCE_DIR}/sigs.h --xml 2> cppcheck.xml &&
+             --project=${CMAKE_CURRENT_BINARY_DIR}/compile_commands.json --xml 2> cppcheck.xml &&
       python3 ${CMAKE_SOURCE_DIR}/scripts/cppcheck-htmlreport.py --file=cppcheck.xml --report-dir=cppcheck
 
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}