Bug fix: Make sure FIX is the 2nd arg to Fun in gckpp_Integrator.F90

KPP/carboncycle/gckpp_Integrator.F90
- Added a kludge: In routine FunTemplate, we now pass FIX (and not VAR)
  as the 2nd argument to Fun.  This error was causing the F variable
  within Fun to be corrupted, which was propagating negatives through
  the code.
- NOTE: We have patched this file for KPP 2.5.0, but a final fix will
  be issued in KPP 3.0.0.  We will eventually rebuild all mechanisms
  with KPP 3.0.0 anyway.
- See KineticPreProcessor/KPP#6 for more info.

Signed-off-by: Bob Yantosca <yantosca@seas.harvard.edu>

KPP/carboncycle/gckpp_Integrator.F90

@@ -223,7 +223,13 @@ SUBROUTINE FunTemplate( Y, Ydot )
     REAL(kind=dp) :: Ydot(NVAR)
 
     !~~~> Compute equation rates and time derivative of variable species
-    CALL Fun( Y, VAR, RCONST, Ydot )
+    !### KLUDGE: FIX must be the 2nd argument to FUN
+    !### See https://github.com/KineticPreProcessor/KPP/issues/60
+    !### We will fix this locally in the KPP-2.5.0 generated code
+    !### but a final fix will be made in KPP 3.0.0.
+    !###   -- Bob Yantosca (18 Oct 2022)
+    !###CALL Fun( Y, VAR, RCONST, Ydot )
+    CALL Fun( Y, FIX, RCONST, Ydot )
 
   END SUBROUTINE FunTemplate