GLSLCompat.glsllib: fix incorrect preprocessor define

jme3-core/src/main/resources/Common/ShaderLib/GLSLCompat.glsllib

@@ -1,4 +1,4 @@
-#if defined _GL_ES_
+#if defined GL_ES
 #  define hfloat highp float
 #  define hvec2  highp vec2
 #  define hvec3  highp vec3