asm/sections: add text/data checking functions for arches to override

Some ports (like the Blackfin arch) have a discontiguous memory map which
means there may be text or data that falls outside of the standard range
of the start/end text/data symbols.  Creating some helper functions allows
these non-standard ports to declare these regions without adversely
affecting anyone else.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>