nuttx: fix <new>

[robbie-sps]

Solved Problem

When adding a new third-party library to our project (HFSM2, FWIW), I found that there were compilation issues with platforms/nuttx/NuttX/include/cxx/new:

/home/robbie/px4/platforms/nuttx/NuttX/include/cxx/new:34:34: error: declaration of 'operator new' as non-function
   34 | inline void* operator new  (std::size_t, void* ptr) { return ptr; }
      |                                  ^~~~~~

Despite the warning from the compiler, the error in my IDE (VSCode) reported that "namespace 'std' has no member 'size_t'"

I found that the compilation error went away when I included the library header later in my code, suggesting that something in the include chain could fix the error

Solution

• Explicitly #include <cstddef> in platforms/nuttx/NuttX/include/cxx/new