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/cmEnableLanguageCommand.h

@@ -28,7 +28,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
     return new cmEnableLanguageCommand;
     }
@@ -39,7 +39,7 @@ public:
    */
   virtual bool InitialPass(std::vector<std::string> const& args,
                            cmExecutionStatus &status);
-  
+
   /**
    * The name of the command as specified in CMakeList.txt.
    */
@@ -52,7 +52,7 @@ public:
     {
     return "Enable a language (CXX/C/Fortran/etc)";
     }
-  
+
   /**
    * More documentation.
    */
@@ -67,7 +67,7 @@ public:
       "If OPTIONAL is used, use the CMAKE_<languageName>_COMPILER_WORKS "
       "variable to check whether the language has been enabled successfully.";
     }
-  
+
   cmTypeMacro(cmEnableLanguageCommand, cmCommand);
 };