added GLSL compat to the pbr shader

jme3-core/src/main/resources/Common/MatDefs/Light/PBRLighting.frag

@@ -1,7 +1,9 @@
+#import "Common/ShaderLib/GLSLCompat.glsllib"
 #import "Common/ShaderLib/Parallax.glsllib"
 #import "Common/ShaderLib/PBR.glsllib"
 #import "Common/ShaderLib/Lighting.glsllib"
 
+
 varying vec2 texCoord;
 #ifdef SEPARATE_TEXCOORD
   varying vec2 texCoord2;

jme3-core/src/main/resources/Common/MatDefs/Light/PBRLighting.vert

@@ -1,6 +1,8 @@
+#import "Common/ShaderLib/GLSLCompat.glsllib"
 #import "Common/ShaderLib/Instancing.glsllib"
 #import "Common/ShaderLib/Skinning.glsllib"
 
+
 uniform vec4 m_BaseColor;
 
 uniform vec4 g_AmbientLightColor;