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/cmVisualStudioGeneratorOptions.cxx

@@ -342,10 +342,10 @@ cmVisualStudioGeneratorOptions
   if(!this->FlagString.empty())
     {
     if(this->Version >= cmLocalVisualStudioGenerator::VS10)
-      { 
+      {
       fout << prefix;
       if(this->Configuration.size())
-        { 
+        {
         this->TargetGenerator->WritePlatformConfigTag(
           "AdditionalOptions",
           this->Configuration.c_str(),