Add blkin-front library

Add blkin-front library to host functions pointers that will be dynamically
resolved during library initialization. This is necessary in order to avoid the
recommended LD_PRELOAD hack. Using dynamic symbol resolving, we lazily load
lttng library and avoid implicitly initializing the library until the
blkin_init() functions gets called. For our purposes, this can happen after the
daemon call (fork) and safely use the lttng infrastructure.
Add debuging symbols during compilation