libroot: remove ATOMIC_FUNCS_ARE_SYSCALLS

GCC knows whether these functions need to be implemented using syscalls
(or more clever solutions like in Linux) and calls libgcc in such case.

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>

src/system/libroot/os/arch/generic/generic_atomic.cpp

@@ -7,8 +7,6 @@
 #include <atomic>
 #include <sys/types.h>
 
-#ifndef ATOMIC_FUNCS_ARE_SYSCALLS
-
 
 extern "C" [[gnu::optimize("omit-frame-pointer")]] void
 atomic_set(int32_t* ptr, int32_t value)
@@ -123,5 +121,3 @@ atomic_get64(int64_t* ptr)
 	return obj.load(std::memory_order_acquire);
 }
 
-
-#endif /* ATOMIC64_FUNCS_ARE_SYSCALLS */