Fix pointer signedness warnings
ada: Remove some useless casts and make some arguments const
Don't pass unverified data as a printf format

A specially crafted output line from an Xcmd could lead CTags to read
arbitrary memory through printf format placeholders in the tag pattern.

E.g. the following output from an Xcmd would trigger this:

`tag	file	/%s %s %s/;"	kind:function`
go: Avoid unnecessary variable shadowing
Don't assign string literal to non-constant pointer