Add explicit dependency on mapcalc.tab.h

and use a .META file to tell make that
both .c and .h are created by one call
to allow for reproducible builds.

Without this change, r.mapcalc and r3.mapcalc
would be rebuilt a 2nd time in a make -j1 run
with slightly varied order of mapcalc.yy.o and mapcalc.tab.o

This might help improve OSGeo#3406

This patch was done while working on reproducible builds for openSUSE.

raster/r.mapcalc/Makefile

@@ -20,7 +20,11 @@ default: multi
 $(BIN)/$(PGM2)$(EXE): LIBES = $(LIBES2)
 $(BIN)/$(PGM3)$(EXE): LIBES = $(LIBES3)
 
-$(OBJDIR)/mapcalc.yy.o: mapcalc.tab.h
+$(OBJDIR)/*.o: $(OBJDIR)/mapcalc.tab.META
+$(OBJDIR)/mapcalc.yy.o: $(OBJDIR)/mapcalc.tab.META
+
+$(OBJDIR)/mapcalc.tab.META: mapcalc.tab.c mapcalc.tab.h
+	touch $(OBJDIR)/mapcalc.tab.META
 
 .SECONDARY: mapcalc.tab.c mapcalc.tab.h mapcalc.output