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/cmInstallProgramsCommand.h

@@ -18,7 +18,7 @@
  * \brief Specifies where to install some programs
  *
  * cmInstallProgramsCommand specifies the relative path where a list of
- * programs should be installed.  
+ * programs should be installed.
  */
 class cmInstallProgramsCommand : public cmCommand
 {
@@ -26,7 +26,7 @@ public:
   /**
    * This is a virtual constructor for the command.
    */
-  virtual cmCommand* Clone() 
+  virtual cmCommand* Clone()
     {
     return new cmInstallProgramsCommand;
     }
@@ -50,7 +50,7 @@ public:
     {
     return "Deprecated. Use the install(PROGRAMS ) command instead.";
     }
-  
+
   /**
    * This is called at the end after all the information
    * specified by the command is accumulated. Most commands do
@@ -87,7 +87,7 @@ public:
       "The directory <dir> is relative to the installation prefix, which "
       "is stored in the variable CMAKE_INSTALL_PREFIX.";
     }
-  
+
   /** This command is kept for compatibility with older CMake versions. */
   virtual bool IsDiscouraged() const
     {