[lmi] gcc-6.3 warnings for wx sha 41045df7

[Greg Chicares]

Vadim--Here are all the warnings I see when compiling wx with
MinGW-w64 gcc-6.3.0 . lmi uses wx as of 41045df7, which is a bit out
of date, but I paste the messages here just in case they're useful.

../src/msw/registry.cpp: In member function 'bool 
wxRegKey::GetNextValue(wxString&, long int&) const':
../src/msw/registry.cpp:1131:3: warning: this 'if' clause does not guard... 
[-Wmisleading-indentation]
   if ( lIndex == -1 )
   ^~
../src/msw/registry.cpp:1134:5: note: ...this statement, but the latter is 
misleadingly indented as if it is guarded by the 'if'
     wxChar  szValueName[1024];                  // @@ use RegQueryInfoKey...
     ^~~~~~

../src/msw/bitmap.cpp: In member function 'void 
wxBitmap::UngetRawData(wxPixelDataBase&)':
../src/msw/bitmap.cpp:1384:12: warning: the compiler can assume that the 
address of 'dataBase' will always evaluate to 'true' [-Waddress]
     if ( !&dataBase )
            ^~~~~~~~
../src/msw/bitmap.cpp:1384:12: warning: the compiler can assume that the 
address of 'dataBase' will always evaluate to 'true' [-Waddress]
../src/msw/bitmap.cpp:1384:5: warning: nonnull argument 'dataBase' compared to 
NULL [-Wnonnull-compare]
     if ( !&dataBase )
     ^~

../src/msw/control.cpp: In member function 'bool 
wxControl::MSWCreateControl(const wxChar*, WXDWORD, const wxPoint&, const 
wxSize&, co
nst wxString&, WXDWORD)':
../src/msw/control.cpp:203:44: warning: nonnull argument 'this' compared to 
NULL [-Wnonnull-compare]
         if ( wxDynamicCastThis(wxTreeCtrl) )
                                            ^
../src/msw/control.cpp:199:44: warning: nonnull argument 'this' compared to 
NULL [-Wnonnull-compare]
         if ( wxDynamicCastThis(wxListCtrl) )
                                            ^

../src/msw/toolbar.cpp: In member function 'virtual wxToolBarToolBase* 
wxToolBar::FindToolForPosition(wxCoord, wxCoord) const':
../src/msw/toolbar.cpp:1629:5: warning: this 'if' clause does not guard... 
[-Wmisleading-indentation]
     if ( index < 0 || (size_t)index >= m_nButtons )
     ^~
../src/msw/toolbar.cpp:1633:9: note: ...this statement, but the latter is 
misleadingly indented as if it is guarded by the 'if'
         return m_tools.Item((size_t)index)->GetData();
         ^~~~~~

../src/generic/datavgen.cpp: In member function 'void 
wxDataViewMainWindow::Collapse(unsigned int)':
../src/generic/datavgen.cpp:3381:5: warning: this 'if' clause does not guard... 
[-Wmisleading-indentation]
     if (!node->HasChildren())
     ^~
../src/generic/datavgen.cpp:3384:9: note: ...this statement, but the latter is 
misleadingly indented as if it is guarded by the 'if'
         if (node->IsOpen())
         ^~