Trying to use libcxx for port a project to Nuttx and I'm having the
following errors:
```
LD: nuttx
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(locale.o): in function
`std::__1::locale::id::__init()':
locale.cpp:(.text+0x1890): undefined reference to `__atomic_fetch_add_4'
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(memory.o): in function
`std::__1::__shared_count::__add_shared()':
memory.cpp:(.text+0x60): undefined reference to `__atomic_fetch_add_4'
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(memory.o): in function
`std::__1::__shared_count::__release_shared()':
memory.cpp:(.text+0x72): undefined reference to `__atomic_fetch_add_4'
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(memory.o): in function
`std::__1::__shared_weak_count::__add_weak()':
memory.cpp:(.text+0x9a): undefined reference to `__atomic_fetch_add_4'
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(memory.o): in function
`std::__1::__shared_weak_count::__release_weak()':
memory.cpp:(.text+0xc0): undefined reference to `__atomic_fetch_add_4'
arm-none-eabi-ld:
/home/castello/projects/N/nuttx/staging/libxx.a(memory.o): in function
`std::__1::__shared_weak_count::lock()':
memory.cpp:(.text+0x102): undefined reference to
`__atomic_compare_exchange_4'
```
I can already build it using the simulator but with arm-none-eabi I'm
not having success. If anyone has any hints or light on what I'm doing
wrong, I'll be very grateful :)
BR,
Matheus Castello
