makepanda: build against OpenEXR 2.4 (MSVC)

Fixes #799
Closes #800

makepanda/makepanda.py

@@ -735,8 +735,11 @@ if (COMPILER == "MSVC"):
             suffix = "-2_2"
         elif os.path.isfile(GetThirdpartyDir() + "openexr/lib/IlmImf-2_3.lib"):
             suffix = "-2_3"
+        elif os.path.isfile(GetThirdpartyDir() + "openexr/lib/IlmImf-2_4.lib"):
+            suffix = "-2_4"
+            LibName("OPENEXR", GetThirdpartyDir() + "openexr/lib/Imath" + suffix + ".lib")
         if os.path.isfile(GetThirdpartyDir() + "openexr/lib/IlmImf" + suffix + "_s.lib"):
-            suffix += "_s"
+            suffix += "_s"  # _s suffix observed for OpenEXR 2.3 only so far
         LibName("OPENEXR", GetThirdpartyDir() + "openexr/lib/IlmImf" + suffix + ".lib")
         LibName("OPENEXR", GetThirdpartyDir() + "openexr/lib/IlmThread" + suffix + ".lib")
         LibName("OPENEXR", GetThirdpartyDir() + "openexr/lib/Iex" + suffix + ".lib")