Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

docs/doxygen/mainpages/copyright.h

@@ -103,7 +103,7 @@ without express or implied warranty.
 @verbinclude "lgpl.txt"
 
 @page page_copyright_xserver The Open Group and DEC License
- 
+
 @verbinclude "xserver.txt"
 
 */