Bug #436: Include guards became unique.

Include guards prevent the multiple inclusion of header files only correctly
if the chosen identifiers are different from others with such a functionality.
The probability for name clashes is reduced by the addition of the project name as a prefix.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Merge pull request #467 from LocutusOfBorg/441-fix

Bug #436: Include guards became unique.