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/cmOutputRequiredFilesCommand.h

@@ -25,7 +25,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
     return new cmOutputRequiredFilesCommand;
     }
@@ -49,7 +49,7 @@ public:
     {
     return "Deprecated.  Approximate C preprocessor dependency scanning.";
     }
-  
+
   /**
    * More documentation.
    */
@@ -72,7 +72,7 @@ public:
     return true;
     }
 
-  
+
   cmTypeMacro(cmOutputRequiredFilesCommand, cmCommand);
   void ListDependencies(cmDependInformation const *info,
                         FILE *fout,