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/cmFindFileCommand.h

@@ -18,7 +18,7 @@
  * \brief Define a command to search for an executable program.
  *
  * cmFindFileCommand is used to define a CMake variable
- * that specifies an executable program. The command searches 
+ * that specifies an executable program. The command searches
  * in the current path (e.g., PATH environment variable) for
  * an executable that matches one of the supplied names.
  */
@@ -29,7 +29,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
     return new cmFindFileCommand;
     }
@@ -42,7 +42,7 @@ public:
     {
     return "Find the full path to a file.";
     }
-  
+
   cmTypeMacro(cmFindFileCommand, cmFindPathCommand);
 protected:
   virtual void GenerateDocumentation();