Remove trailing commas from enums

I do sympathize with the motivation for these trailing commas, but
they cause silly build failures with --enable-compile-warnings=error
(which is used at least by the Debian/Ubuntu package).

  CXX      parseraction.o
In file included from terminal.h:42:0,
                 from parseraction.cc:37:
terminalframebuffer.h:200:39: error: comma at end of enumerator list [-Werror=pedantic]
       MOUSE_REPORTING_ANY_EVENT = 1003,
                                       ^
terminalframebuffer.h:210:34: error: comma at end of enumerator list [-Werror=pedantic]
       MOUSE_ENCODING_URXVT = 1015,
                                  ^
cc1plus: all warnings being treated as errors
Makefile:354: recipe for target 'parseraction.o' failed

Signed-off-by: Anders Kaseorg <andersk@mit.edu>