Build failing on latest gcc

[DannyParker0001]

Outputs from configure and build commands are:
./waf configure -T debug > configure.log 2>&1
./waf build -v > compile.log 2>&1

Error is

../engine/gl_matsysiface.cpp: In function ‘void DebugDrawLightmapAtCrossHair()’:
../engine/gl_matsysiface.cpp:975:31: error: ordered comparison of pointer with integer zero (‘SurfaceHandle_t’ {aka ‘msurface2_t*’} and ‘int’)
  975 |         if( s_CrossHairSurfID <= 0 )
      |             ~~~~~~~~~~~~~~~~~~^~~~
In file included from ../public/tier1/utlsymbol.h:17,
                 from ../engine/render_pch.h:13,
                 from ../engine/gl_matsysiface.cpp:12: