[Bug-xorriso] `make install` parallelized failure in xorriso 1.4.2

[ilove zfs]

(See https://github.com/Homebrew/homebrew-core/pull/1941)

This seems to be a regression in 1.4.2, as I cannot reproduce the issue with 1.4.0.

The error is

```

 mkdir: /usr/local/Cellar/xorriso/1.4.2/bin: File exists
make[1]: *** [install-binPROGRAMS] Error 1
make[1]: *** Waiting for unfinished jobs....
...
make: *** [install-am] Error 2

```

I have found the following workarounds to be successful:

(a) de-parallelizing just `make install`

(b) running autoreconf -fiv

(c) replacing the install-sh in the tarball with my local share/automake-1.15/install-sh (this is the reason (b) works)

(d) setting MKDIR_P="mkdir -p" instead of the default, which is "./install-sh -c -d" (again, another way of working around the issue with the tarball's install-sh)

However, I'm not sure precisely what changed between 1.4.0 and 1.4.2 to trigger the bug.

(iMac running OS X 10.11.5, if relevant)