Use 3.18 syscall instrumentation for MIPS32

Update the MIPS32 syscall instrumentation to 3.18

Fix: Move pipe override to the arch specific pointers_override.h

Implement lttng test module

Cleanup: remove logically dead code

Fix: filter validator use after free

Fix: use after free in channel release

Fix: non-enabler events should be disabled by default

Fix: build failure on 2.6.36

Cleanup: split bdi_dirty_ratelimit with ifdef into separate macros

Fix: writeback instrumentation for 4.2 kernels

Fix: mm_page_alloc_extfrag instrumentation for kernel 3.18.10

Add stream instance id to the packet header

Add a packet sequence number

Fix: kmem probe with Ubuntu 3.13 kernels