Drop flex_arrays

All existing users have been converted to generic radix trees

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kent Overstreet <[email protected]>
Acked-by: Dave Hansen <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: Marcelo Ricardo Leitner <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Neil Horman <[email protected]>
Cc: Paul Moore <[email protected]>
Cc: Pravin B Shelar <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Stephen Smalley <[email protected]>
Cc: Vlad Yasevich <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>