Fix four minor cppcheck warnings

Fix four minor cppcheck warnings

- uninitvar:src/ccache.cpp:3422: Uninitialized variable: ctx
- redundantInitialization:src/legacy_util.cpp:1067: Redundant initialization
  for 'q'. The initialized value is overwritten before it is read.
- constVariable:src/stats.cpp:429: Variable 'ctx' can be declared with const
- variableScope:src/Util.cpp:404: The scope of the variable 'right' can be
  reduced.