Revert "GLSL: Provide a dynamic #version directive to the shaders, in line with OpenGL standards"

This reverts commit 0345d09.

Author: Echelon9

code/graphics/gropenglshader.cpp

@@ -304,10 +304,6 @@ void opengl_shader_shutdown()
 static char *opengl_load_shader(shader_type type_id, char *filename, int flags)
 {
 	SCP_string sflags;
-	char version_string[15];
-
-	sprintf(version_string, "#version %d \n", GLSL_version);
-	sflags += version_string;
 
 #ifdef __APPLE__
 	sflags += "#define APPLE\n";