Remove trailing whitespace from most CMake and C/C++ code

Our Git commit hooks disallow modification or addition of lines with
trailing whitespace.  Wipe out all remnants of trailing whitespace
everywhere except third-party code.

Run the following shell code:

git ls-files -z -- \
 bootstrap doxygen.config '*.readme' \
 '*.c' '*.cmake' '*.cpp' '*.cxx' \
 '*.el' '*.f' '*.f90' '*.h' '*.in' '*.in.l' '*.java' \
 '*.mm' '*.pike' '*.py' '*.txt' '*.vim' |
egrep -z -v '^(Utilities/cm|Source/(kwsys|CursesDialog/form)/)' |
egrep -z -v '^(Modules/CPack\..*\.in)' |
xargs -0 sed -i 's/ \+$//'

Source/cmWriteFileCommand.cxx

@@ -71,7 +71,7 @@ bool cmWriteFileCommand
     }
   // If GetPermissions fails, pretend like it is ok. File open will fail if
   // the file is not writable
-  std::ofstream file(fileName.c_str(), 
+  std::ofstream file(fileName.c_str(),
                      overwrite?std::ios::out : std::ios::app);
   if ( !file )
     {