used enable instead of require for the textureCubeLod extension

jme3-core/src/main/resources/Common/MatDefs/ShaderNodes/Environment/envMapping100.frag

@@ -1,4 +1,4 @@
-#extension GL_ARB_shader_texture_lod : require
+#extension GL_ARB_shader_texture_lod : enable
 void main(){
         //@input vec3 refVec the reflection vector
     //@input samplerCube cubeMap the cube map

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

@@ -1,4 +1,4 @@
-#extension GL_ARB_shader_texture_lod : require
+#extension GL_ARB_shader_texture_lod : enable
 #ifndef PI
     #define PI 3.14159265358979323846264
 #endif