Moved Performer and Inventor plugins into block protected to only compile when not using GLES.

src/osgPlugins/CMakeLists.txt

@@ -131,8 +131,14 @@ IF(ZLIB_FOUND)
     ADD_SUBDIRECTORY(gz)
 ENDIF()
 
-IF(INVENTOR_FOUND)
-    ADD_SUBDIRECTORY(Inventor)
+IF(NOT OSG_GLES1_AVAILABLE AND NOT OSG_GLES2_AVAILABLE)
+    IF(INVENTOR_FOUND)
+        ADD_SUBDIRECTORY(Inventor)
+    ENDIF()
+
+    IF(PERFORMER_FOUND)
+        ADD_SUBDIRECTORY(pfb)
+    ENDIF()
 ENDIF()
 
 IF(OPENVRML_FOUND)
@@ -158,10 +164,6 @@ ADD_SUBDIRECTORY(OpenFlight)
 ADD_SUBDIRECTORY(geo)
 ADD_SUBDIRECTORY(obj)
 
-IF(PERFORMER_FOUND)
-    ADD_SUBDIRECTORY(pfb)
-ENDIF()
-
 ADD_SUBDIRECTORY(pic)
 ADD_SUBDIRECTORY(stl)
 ADD_SUBDIRECTORY(3ds)