Bug #177: Include guards became consistent.

Some include guards did not fit to the expected naming convention of the
C language standard.
https://www.securecoding.cert.org/confluence/display/seccode/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier

This detail was fixed by the addition of the project name as a prefix.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Bug #177: Clean-up of reserved identifier violations

Some identifiers did not fit to the expected naming convention of the
C language standard.
https://www.securecoding.cert.org/confluence/display/seccode/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier

This detail was fixed by the deletion of leading underscores.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>