tests: Fix faulty merge for shaderpipeline GLSL include test

tests/display/glsl_include.vert

@@ -2,7 +2,9 @@
 
 #extension GL_GOOGLE_include_directive : require
 
-#include "glsl_include_inputs.vert"
+#include "glsl_include_inputs.glsl"
+
+in vec4 p3d_Vertex;
 
 void main() {
   gl_Position = p3d_ModelViewProjectionMatrix * p3d_Vertex;