ClangFormat: set InsertNewlineAtEOF to true (#1358)

Author: eramongodb

.clang-format

@@ -200,7 +200,7 @@ IndentRequiresClause: true
 IndentWidth:     4
 IndentWrappedFunctionNames: false
 InsertBraces:    false
-InsertNewlineAtEOF: false
+InsertNewlineAtEOF: true
 InsertTrailingCommas: None
 IntegerLiteralSeparator:
   Binary:          0