various tests of flaming monsters

This change adds a new flaming() macro and uses it in several places
where the list of flaming monsters was tested.  on_fire() didn't list
salamanders as already being on fire, but should have.  A couple other
cases were not updated to include flaming sphere.

include/mondata.h

@@ -48,6 +48,10 @@
 #define has_horns(ptr)		(num_horns(ptr) > 0)
 #define is_whirly(ptr)		((ptr)->mlet == S_VORTEX || \
 				 (ptr) == &mons[PM_AIR_ELEMENTAL])
+#define flaming(ptr)		((ptr) == &mons[PM_FIRE_VORTEX] || \
+				 (ptr) == &mons[PM_FLAMING_SPHERE] || \
+				 (ptr) == &mons[PM_FIRE_ELEMENTAL] || \
+				 (ptr) == &mons[PM_SALAMANDER])
 #define is_silent(ptr)		((ptr)->msound == MS_SILENT)
 #define unsolid(ptr)		(((ptr)->mflags1 & M1_UNSOLID) != 0L)
 #define mindless(ptr)		(((ptr)->mflags1 & M1_MINDLESS) != 0L)