Update idl_gen_general.cpp

There is a bug in creating a C# table when it includes a field of type 'BOOL'. The problem is that the generate C# code is as follows:
  "bool SampleValue = 0;"
This will fail to compile, because in C# this fails, it needs to be generated as:
 "bool SampleValue = false;"

The error is in line ~510

Change-Id: I77f6eea0f269b0540dbeb462602fc447cb69237d