add patch to workaround sed 4.6 regression/changed behavior

add patch to workaround sed 4.6 regression/changed behavior

sample input (include/VBox/Graphics/VBoxVideoGuest.h)

DECLHIDDEN(int) VBoxHGSMIGetModeHints(PHGSMIGUESTCOMMANDCONTEXT pCtx,
                                      unsigned cScreens, VBVAMODEHINT *paHints);

incorrect output:

LC_ALL=C sed -f ./src/VBox/Additions/linux/drm/indent.sed include/VBox/Graphics/VBoxVideoGuest.h
...
int hgsmi_get_mode_hints(PHGSMIGUESTCOMMANDCONTEXT ctx,
						unsigned screens, struct vbva_modehint *hints);
...

correct output:

LC_ALL=C.UTF-8 sed -f ./src/VBox/Additions/linux/drm/indent.sed include/VBox/Graphics/VBoxVideoGuest.h
...
int hgsmi_get_mode_hints(struct gen_pool * ctx,
						unsigned screens, struct vbva_modehint *hints);
...

PHGSMIGUESTCOMMANDCONTEXT -> struct gen_pool * is not done