[Linux] (Some) addons compile fail, missing include for strstr()

/.../AngelScript/sdk/add_on/scriptfile/scriptfilesystem.cpp:90:6: error: ‘strstr’ was not declared in this scope
  if( strstr(asGetLibraryOptions(), "AS_MAX_PORTABILITY") )
      ^~~~~~
/.../AngelScript/sdk/add_on/scriptfile/scriptfilesystem.cpp:90:6: note: ‘strstr’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?

g++ 8, 9, 10