dtrace(1) couldn't compile due to type redefintion errors. Below is a sample from the compiler output:
```
/usr/include/x86/_types.h:109:20: error: redefinition of typedef '__uintfptr_t' is a C11 feature [-Werror,-
typedef __uint64_t __uintfptr_t;
^
/mnt/src/sys/sys/_types.h:78:20: note: previous definition is here
typedef __uint64_t __uintfptr_t;
^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
*** Error code 1
```
I'm not sure if that's the correct fix, but it works. If it is, feel
free to remove the line altogether.