glapi: Don't search through subdirs from glapitable.h

Because meson won't put it in that folder.

Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/mapi/glapi/tests/check_table.cpp

@@ -25,7 +25,7 @@
 #include "main/glheader.h"
 
 #include "glapi/glapi.h"
-#include "glapi/glapitable.h"
+#include "glapitable.h"
 
 struct name_offset {
    const char *name;