(readline): When creating a relative file name from a

(readline): When creating a relative file name from a
#line directive, leave the file name alone.  The previous
behaviour was to make it relative to the tags file directory,
under the hypothesis that the #line directive file name was
relative to the directory of the tagged file.  That hypothesis is
wrong with Cpp and Lex.

(Makefile_targets): Do not include spaces in tag names.