Revise C++ coding style using clang-format

Run the `Utilities/Scripts/clang-format.bash` script to update
all our C++ code to a new style defined by `.clang-format`.
Use `clang-format` version 3.8.

* If you reached this commit for a line in `git blame`, re-run the blame
  operation starting at the parent of this commit to see older history
  for the content.

* See the parent commit for instructions to rebase a change across this
  style transition commit.

Source/cmMakefileExecutableTargetGenerator.h

@@ -14,7 +14,7 @@
 
 #include "cmMakefileTargetGenerator.h"
 
-class cmMakefileExecutableTargetGenerator: public cmMakefileTargetGenerator
+class cmMakefileExecutableTargetGenerator : public cmMakefileTargetGenerator
 {
 public:
   cmMakefileExecutableTargetGenerator(cmGeneratorTarget* target);