Add CONTRIBUTING.rst, and move (corrected) dev instructions into it.

CONTRIBUTING.rst

+CONTRIBUTING
+============
+
+To contribute code or documentation, submit a pull request at the
+`source repository website
+<https://code.uplex.de/uplex-varnish/libvmod-backend_dyn>`_.
+
+If you have a problem or discover a bug, you can post an `issue
+<https://code.uplex.de/uplex-varnish/libvmod-backend_dyn/issues>`_ at
+the website. You can also write to <varnish-support@uplex.de>.
+
+For developers
+--------------
+
+The build specifies C99 conformance, all compiler warnings turned on,
+and all warnings considered errors (compiler options ``-std=c99
+-Werror -Wall -Wextra``).
+
+The VMOD has been tested with both the gcc and clang compilers, and
+should always compile and test successfully with both of them.
+
+By default, ``CFLAGS`` is set to ``-g -O2``, so that symbols are
+included in the shared library, and optimization is at level
+``O2``. To change or disable these options, set ``CFLAGS`` explicitly
+before calling ``make`` (it may be set to the empty string).
+
+For development/debugging cycles, the ``configure`` option
+``--enable-debugging`` is recommended (off by default). This will turn
+off optimizations and function inlining, so that a debugger will step
+through the code as expected.

README.rst

@@ -322,28 +322,6 @@ INSTALLATION
 
 See `INSTALL.rst <INSTALL.rst>`_ in the source repository.
 
-For developers
---------------
-
-As with Varnish, you can use these ``configure`` options for developer
-builds:
-
-*  ``--enable-developer-warnings``
-
-   * Set stricter error and warning levels for compilation. The VMOD
-     MUST always build successfully with this option enabled.
-
-* ``--enable-debugging-symbols``
-
-   * Make the VMOD's symbols available to debuggers, core dumps and so forth.
-
-* ``--enable-stack-protector``
-
-   * Emit extra code to avoid buffer overflows
-
-See ``configure --help`` for a full list of configuration options and
-environment variables.
-
 AUTHOR
 ======
 

src/vmod.vcc

@@ -279,28 +279,6 @@ INSTALLATION
 
 See `INSTALL.rst <INSTALL.rst>`_ in the source repository.
 
-For developers
---------------
-
-As with Varnish, you can use these ``configure`` options for developer
-builds:
-
-*  ``--enable-developer-warnings``
-
-   * Set stricter error and warning levels for compilation. The VMOD
-     MUST always build successfully with this option enabled.
-
-* ``--enable-debugging-symbols``
-
-   * Make the VMOD's symbols available to debuggers, core dumps and so forth.
-
-* ``--enable-stack-protector``
-
-   * Emit extra code to avoid buffer overflows
-
-See ``configure --help`` for a full list of configuration options and
-environment variables.
-
 AUTHOR
 ======