Remove Boost version "1_45" baked into library names.

On Windows, LLPrimitive.cmake named four Boost libraries with names ending in
the string 1_45. Now that we're trying to upgrade Boost to 1.52, those
suffixes are inappropriate. Fortunately the libraries in our current Boost
package do not have version-stamped names, so we hope this fix can survive
for several Boost upgrades to come.