[PATCH] [RFC] Use llvm-symbolizer to symbolize LLVM/Clang crash dumps

[Ed Maste]

/proc/self/exe equivalent for FreeBSD:

```
#include <sys/param.h>
#include <sys/sysctl.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>

int
main(int argc, char *argv[])
{
        char buf[MAXPATHLEN];
        int error, name[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME };
        size_t len = sizeof(buf);

        name[3] = getpid();
        error = sysctl(name, 4, buf, &len, NULL, 0);
        if (error != 0 && errno != ESRCH)
                warn("sysctl: kern.proc.pathname: %d", getpid());
        if (len == 0)
                buf[0] = '\0';

        printf("kern.proc.pathname = %s\n", buf);
}
```

I'll clean this up and implement it for `lib/Support/Unix/Path.inc`

http://reviews.llvm.org/D5610