Fix GAL option spin button layout

These need to not be wxEXPAND and to be vertically centred
to match the adjacent text controls.

Fixes: lp:1804461
* https://bugs.launchpad.net/kicad/+bug/1804461

(cherry picked from commit 203019d959)

common/widgets/gal_options_panel.cpp

@@ -100,7 +100,7 @@ GAL_OPTIONS_PANEL::GAL_OPTIONS_PANEL( wxWindow* aParent, KIGFX::GAL_DISPLAY_OPTI
 
         m_gridLineWidthSpinBtn = new wxSpinButton( sGridSettings->GetStaticBox(),
                 wxID_ANY, wxDefaultPosition, wxDefaultSize, wxSP_ARROW_KEYS );
-        sGridSettingsGrid->Add( m_gridLineWidthSpinBtn, 0, wxEXPAND | wxALL, 0 );
+        sGridSettingsGrid->Add( m_gridLineWidthSpinBtn, 0, wxALL | wxALIGN_CENTER_VERTICAL, 0 );
 
         l_gridLineWidthUnits = new wxStaticText( sGridSettings->GetStaticBox(),
                 wxID_ANY, _( "px" ) );
@@ -117,7 +117,7 @@ GAL_OPTIONS_PANEL::GAL_OPTIONS_PANEL( wxWindow* aParent, KIGFX::GAL_DISPLAY_OPTI
 
         m_gridMinSpacingSpinBtn = new wxSpinButton( sGridSettings->GetStaticBox(),
                 wxID_ANY, wxDefaultPosition, wxDefaultSize, wxSP_ARROW_KEYS );
-        sGridSettingsGrid->Add( m_gridMinSpacingSpinBtn, 0, wxEXPAND | wxALL, 0 );
+        sGridSettingsGrid->Add( m_gridMinSpacingSpinBtn, 0, wxALL | wxALIGN_CENTER_VERTICAL, 0 );
 
         l_gridMinSpacingUnits = new wxStaticText( sGridSettings->GetStaticBox(),
                 wxID_ANY, _( "px" ) );