Placeholder for simplified system library exception.

The definition of "System Libraries" in GPLv3 (used in the
Corresponding Source definition) is unnecessarily complex and
difficult to parse and understand. This commit replaces it with a
definition based on the GPLv2 system library exception but with a few
changes adapted from the version of the system library exception in
the first dicussion draft of GPLv3.

Further work on this definition is necessary; this version can be seen
as something of a placeholder.

GPL.next

@@ -48,16 +48,12 @@ standard defined by a recognized standards body, or, in the case of
 interfaces specified for a particular programming language, one that
 is widely used among developers working in that language.
 
-  The "System Libraries" of an executable work include anything, other
+  "System Libraries" of an executable work means any part of the work
-than the work as a whole, that (a) is included in the normal form of
+that is normally distributed (in either source code or object code
-packaging a Major Component, but which is not part of that Major
+form) with (i) the major components (kernel, window system, and so on)
-Component, and (b) serves only to enable use of the work with that
+of the operating system on which the executable runs or (ii) a
-Major Component, or to implement a Standard Interface for which an
+compiler used to produce the executable or (iii) an object code
-implementation is available to the public in source code form.  A
+interpreter used to run the executable.
-"Major Component", in this context, means a major essential component
-(kernel, window system, and so on) of the specific operating system
-(if any) on which the executable work runs, or a compiler used to
-produce the work, or an object code interpreter used to run it.
 
   The "Corresponding Source" for a work in object code form means all
 the source code needed to generate, install, and (for an executable