Fix for Cursor rendering on Linux+EGL+Nvidia in accelerated graphics mode

EGL/NVidia can sometimes clip the cursor based on its plane regardless of the depth mask.  This avoids the issue by forcing the cursor up over the existing plane.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/12183

common/gal/opengl/opengl_gal.cpp

@@ -2700,6 +2700,10 @@ void OPENGL_GAL::blitCursor()
     glLineWidth( 1.0 );
     glColor4d( color.r, color.g, color.b, color.a );
 
+    glMatrixMode( GL_PROJECTION );
+    glPushMatrix();
+    glTranslated( 0, 0, -0.5 );
+
     glBegin( GL_LINES );
 
     if( m_crossHairMode == CROSS_HAIR_MODE::FULLSCREEN_DIAGONAL )
@@ -2743,6 +2747,8 @@ void OPENGL_GAL::blitCursor()
 
     glEnd();
 
+    glPopMatrix();
+
     if( depthTestEnabled )
         glEnable( GL_DEPTH_TEST );
 }