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/cmGetTargetPropertyCommand.h

@@ -17,7 +17,7 @@
 class cmGetTargetPropertyCommand : public cmCommand
 {
 public:
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
       return new cmGetTargetPropertyCommand;
     }
@@ -41,7 +41,7 @@ public:
     {
     return "Get a property from a target.";
     }
-  
+
   /**
    * Longer documentation.
    */
@@ -59,7 +59,7 @@ public:
         "\n"
         "See also the more general get_property() command.";
     }
-  
+
   cmTypeMacro(cmGetTargetPropertyCommand, cmCommand);
 };