libipt: add struct pt_time

Add struct pt_time to hold timing related stuff.  Also store the current
core:bus ratio.

Change-Id: Ic966af1c0fda9c30f2c5e09a06705353af784f43
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
libipt: add a core:bus ratio query

Add a core:bus ratio query to the query and insn layers. This is useful when
a client using the high level insn layer wants to track frequency changes.
Semantics are the same as with TSC queries.

Change-Id: I8933b4045c0c18f4beec47a7fd2344d07c425f6a
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>