[bug #34191] +bundleForClass: doesn't with framework bundles

[Chris Armstrong]

Follow-up Comment #1, bug #34191 (project gnustep):

This problem appears to be a bit more complicated than +bundleForClass not
working.

The cause is +[NSBundle intialize] not finding the NSFramework_EtoileUI class,
which doesn't exist at the time it was called. NSBundle builds a list of
frameworks when its +intialize method is called, by searching the runtime for
classes that begin with "NSFramework_". These classes are placeholders,
generated by gnustep-make, that indicate that a shared library is in fact a
framework, and like bundles, can contain resources to be loaded.

In this case, EtoileUI was accidentally triggering the +[NSBundle intialize]
method before NSFramework_EtoileUI had been loaded. It does this by calling
GNUstep classes (such as NSString and NSSet) from a +load method in a category
on NSView. +load methods are implemented by creating constructor functions
i.e. __attribute__((constructor)) that are called when a shared library is
loaded. This is a problem because these constructor functions also seem to be
used to register classes with the runtime when a shared library is loaded. 

+load is not supposed to be used for anything other than very simple, C-based
intialisation, because as documented here [1], +load is not guaranteed to be
called at a time when other classes are ready. By doing this, NSBundle
initializes before all other classes are loaded and builds an incomplete
framework list.

The correct solution is not use +load for anything other than calling classes
in the same file, but this still means that NSBundle is vulnerable to being
initialised to early and building incomplete framework meta-data. NSBundle
cannot easily convert its initialisation to a +load method either, which would
prevent the issue from occurring.

[1]
http://gcc.gnu.org/onlinedocs/gcc-4.6.1/gcc/What-you-can-and-what-you-cannot-do-in-_002bload.html#What-you-can-and-what-you-cannot-do-in-_002bload

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