[foreign] Instructions for using libraries on Windows

[Jorn Vernee]

Hi,

I have updated panama_foreign.md with instructions for jextracting and 
running OpenGL and Python. I have also tried other Windows applicable 
libraries, here were the issues:

LAPACK & BLAS: require libgfortran-3 as a dependency, which I couldn't 
find a binary distro for so quickly. (MINGW has a package for it, but 
only libgfortran-4)

Tensorflow: is crashing jextract with a stack overflow error.

```
     Exception in thread "main" java.lang.StackOverflowError
         at 
jdk.internal.clang/jdk.internal.clang.StructType.<init>(StructType.java:37)
         at 
jdk.internal.clang/jdk.internal.clang.StructType.<init>(StructType.java:32)
         at 
jdk.internal.clang/jdk.internal.clang.Type.<init>(Type.java:30)
         at 
jdk.internal.clang/jdk.internal.clang.Type.canonicalType(Native Method)
         at 
jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:134)
         at 
jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:134)
         at 
jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:134)
         at 
jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:134)
         ...
```

FWIW, you made a note about needing to pass `-C -c -C c++` to jextract 
so it doesn't interpret some methods as varargs. I've tried without 
those flags and am observing the same vararg problem, but in that case 
extraction does succeed.

The other libraries libproc, readline, and unistd don't seem applicable 
to Windows. I will be on the lookout for Windows specific examples that 
could be interesting.

The `make update-build-doc` does not work on windows [1], so I ask that 
you generate the .html dos for me instead.

Here is the updated panama_foreign.md: 
http://cr.openjdk.java.net/~jvernee/panama/panama_foreign.md

Jorn

[1] : 
https://mail.openjdk.java.net/pipermail/build-dev/2019-January/024666.html