[LAA] Enable symbolic stride speculation for all LAA clients

This is a functional change for LLE and LDist.  The other clients (LV,
LVerLICM) already had this explicitly enabled.

The temporary boolean parameter to LAA is removed that allowed turning
off speculation of symbolic strides.  This makes LAA's caching interface
LAA::getInfo only take the loop as the parameter.  This makes the
interface more friendly to the new Pass Manager.

The flag -enable-mem-access-versioning is moved from LV to a LAA which
now allows turning off speculation globally.

llvm-svn: 273064