flex 2.6.3 introduces symbol remapping through macro definitions. hence the
change appears bigger than one would expect from a minor version upgrade.

In addition some manual cleanup that had to be done previously is now
obsolete. namely:
  - the size_t cast of _yybytes_len in yy_scan_bytes
    (i is now also defined int and not size_t anymore)
  - the redefinition of yyl within yy_find_action
    (yyl is now already defined as int)

Line number preprocessor directives (#line) were previously generated into
the c source file. This actually breaks debugging as debuggers have a hard
time finding the original cmDependsJavaLexer.in.l and mapping the current
instruction to a meaningful location within that file.

The prefix "cmDependsJava_yy" can already be set as %option directly.

For convenience also provide a sed command for all the manual steps that
need to be done after generating.

Signed-off-by: Matthias Maennich <matthias@maennich.net>