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/cmStringCommand.h

@@ -30,7 +30,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
     return new cmStringCommand;
     }
@@ -59,7 +59,7 @@ public:
     {
     return "String operations.";
     }
-  
+
   /**
    * More documentation.
    */
@@ -143,7 +143,7 @@ public:
       "             by all regular expression-related commands, including \n"
       "             e.g. if( MATCHES ), in the variables CMAKE_MATCH_(0..9).";
     }
-  
+
   cmTypeMacro(cmStringCommand, cmCommand);
   static void ClearMatches(cmMakefile* mf);
   static void StoreMatches(cmMakefile* mf, cmsys::RegularExpression& re);