Fix a few typos

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
diff --git a/src/glx/indirect_vertex_array.c b/src/glx/indirect_vertex_array.c
index 0025cbb..2bf2ff1 100644
--- a/src/glx/indirect_vertex_array.c
+++ b/src/glx/indirect_vertex_array.c
@@ -281,7 +281,7 @@
    i += vertex_program_attribs;
 
 
-   /* Vertex array *must* be last becuase of the way that
+   /* Vertex array *must* be last because of the way that
     * emit_DrawArrays_none works.
     */