Remove some cognitive load by renaming clang/Serialization/Module.h to
clang/Serialization/ModuleFile.h, since it declares the ModuleFile
class. This also makes editing a bit easier, since the basename of the
file no long conflicts with clang/Basic/Module.h, which declares the
Module class. Also move lib/Serialization/Module.cpp to
lib/Serialization/ModuleFile.cpp.
Duncan P. N. Exon Smith