Revise C++ coding style using clang-format-6.0

Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`.  Use `clang-format` version 6.0.

* 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.

Tests/CustomCommand/wrapper.cxx

@@ -17,9 +17,10 @@ int main(int argc, char* argv[])
 #ifdef CMAKE_INTDIR
   const char* cfg = (argc >= 4) ? argv[3] : "";
   if (strcmp(cfg, CMAKE_INTDIR) != 0) {
-    fprintf(stderr, "Did not receive expected configuration argument:\n"
-                    "  expected [" CMAKE_INTDIR "]\n"
-                    "  received [%s]\n",
+    fprintf(stderr,
+            "Did not receive expected configuration argument:\n"
+            "  expected [" CMAKE_INTDIR "]\n"
+            "  received [%s]\n",
             cfg);
     return 1;
   }