Added a few vm_object debug functions. Fixed few bugs.

Next issues: For every read fault, the fault must traverse the
vma's object stack until the page is found. The problem was that
we were only searching the first object, that object was a writable
shadow, and the shadow didn't have the read-only page, and the 0
return value was interpreted with IS_ERR() and failed, so address
0 was mapped into the location, and QEMU blew off.

include/l4/glue/arm/memory.h

@@ -25,7 +25,7 @@
 #define SECTION_MASK			ARM_SECTION_MASK
 #define SECTION_BITS			ARM_SECTION_BITS
 
-/* Aligns to the upper page (ceiling) */
+/* Aligns to the upper page (ceiling) FIXME: Must add a wraparound checker. */
 #define page_align_up(addr) 		((((unsigned int)(addr)) + \
 					  (PAGE_SIZE - 1)) & \
 					 (~PAGE_MASK))