LCOV version 1.13

lcov: Finalize release 1.12

 - Use full git describe output as tool version
 - Update version numbers and last-changed-dates in man pages,
   spec and README file
 - Replace static CHANGES file with git log
 - Switch Makefile logic to use mktemp for generating a temporary
   directory

Signed-off-by: Peter Oberparleiter <[email protected]>

lcov: finalizing release 1.11