This optimisation divides by 2.5 the time (user+sys) needed to read

This optimisation divides by 2.5 the time (user+sys) needed to read
the inlined info of a big executable.
On a slow pentium, reading the inline info now takes 5.5 seconds.

The optimisation consists in having per dw3 abbreviation a structure
allowing to skip efficiently the non interesting DIEs (i.e. the DIEs
the parse_inl_DIE is not interested in).
Mostly, the idea is to avoid calling the image abstraction, and replace
this by just advancing the cursor (i.e. addition rather than a bunch
of function calls to read the data).

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14075