#531 : reuse old style signal handler

[lidaobing]

$ /usr/local/bin/iptux &
[1] 577181
$ kill -11 `pgrep iptux`
Error: signal 11:
$ /usr/local/bin/iptux(+0x4c772)[0x55a7bcf86772]
/lib/x86_64-linux-gnu/libc.so.6(+0x42520)[0x7ff0b8642520]
/lib/x86_64-linux-gnu/libc.so.6(__poll+0x4f)[0x7ff0b8718bcf]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(+0xab1f6)[0x7ff0b8e311f6]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_main_context_iteration+0x33)[0x7ff0b8dd93e3]
/lib/x86_64-linux-gnu/libgio-2.0.so.0(g_application_run+0x1a5)[0x7ff0b9000fb5]
/usr/local/bin/iptux(_ZN5iptux11Application3runEiPPc+0x46)[0x55a7bcf88426]
/usr/local/bin/iptux(main+0x307)[0x55a7bcf86b16]
/lib/x86_64-linux-gnu/libc.so.6(+0x29d90)[0x7ff0b8629d90]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80)[0x7ff0b8629e40]
/usr/local/bin/iptux(_start+0x25)[0x55a7bcf85f55]

[1]+  Exit 1                  /usr/local/bin/iptux
$ echo '/usr/local/bin/iptux(_ZN5iptux11Application3runEiPPc+0x46)[0x55a7bcf88426]' | c++filt
/usr/local/bin/iptux(iptux::Application::run(int, char**)+0x46)[0x55a7bcf88426]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.26%. Comparing base (59cdb2c) to head (90b21d8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #532      +/-   ##
==========================================
+ Coverage   45.25%   45.26%   +0.01%     
==========================================
  Files          61       61              
  Lines        7549     7549              
==========================================
+ Hits         3416     3417       +1     
+ Misses       4133     4132       -1     

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[lidaobing]

/close #531