clang-format: adjust layout of structs

clang-format: adjust layout of structs

Some structs are packed by clang-format, leaving the closing brace
n the same line as the data:

char *known[] = {"color-xterm", "cygwin", "eterm",  "kterm", "nxterm",
                 "putty",       "rxvt",   "screen", "xterm", NULL};

By inserting a comma after the last data item (allowed by C99),
clang-format produces a more pleasant-looking layout:

char *known[] = {
    "color-xterm", "cygwin", "eterm",  "kterm", "nxterm",
    "putty",       "rxvt",   "screen", "xterm", NULL,
};