[Mac] Code sign for gdb

• 在 Mac上以 MacPort 安裝 gdb 後, 會顯示

•  gdb has the following notes:
      You will need to codesign /opt/local/bin/ggdb
      
      See
      https://sourceware.org/gdb/wiki/BuildingOnDarwin#Giving_gdb_permission_to_control_other_processes
      for more information. 

• 請按照網頁所列方法為 gdb 做 code sign. 否則在 gdb run的時候會顯示以下 error message:

• Unable to find Mach task port for process-id 72241: (os/kern) failure (0x5).
   (please check gdb is codesigned - see taskgated(8))