Add missing newline in help text for flatc.

Tested: Help text displays correctly now.
Change-Id: Ibbdc810ae41e24321860879064bdc64f78a67cb9

src/flatc.cpp

@@ -88,7 +88,7 @@ static void Error(const std::string &err, bool usage, bool show_exe_name) {
       "                  generated file depends on (C++).\n"
       "  --gen-mutable   Generate accessors that can mutate buffers in-place.\n"
       "  --raw-binary    Allow binaries without file_indentifier to be read.\n"
-      "                  This may crash flatc given a mismatched schema."
+      "                  This may crash flatc given a mismatched schema.\n"
       "  --proto         Input is a .proto, translate to .fbs.\n"
       "FILEs may depend on declarations in earlier files.\n"
       "FILEs after the -- must be binary flatbuffer format files.\n"