make depend, inspection of builtins.c/h and make
Generated code in builtins.h looks like:
```
static inline int
safe_builtin_always(int idx)
{
if (idx == BLTINCMD ||
idx == COMMANDCMD ||
idx == ECHOCMD ||
idx == FALSECMD ||
idx == JOBIDCMD ||
idx == JOBSCMD ||
idx == KILLCMD ||
idx == PRINTFCMD ||
idx == PWDCMD ||
idx == TESTCMD ||
idx == TIMESCMD ||
idx == TRUECMD ||
idx == TYPECMD)
return (1);
return(0);
}
```