libretro-mame: add additional patch from dhewg

Signed-off-by: Matthias Reichl <hias@horus.com>

packages/emulation/libretro-mame/patches/build.patch

@@ -1,3 +1,28 @@
+--- a/makefile	2020-01-31 06:50:07.043158899 +0100
++++ b/makefile	2020-01-31 06:43:35.696492947 +0100
+@@ -1713,12 +1713,11 @@
+ 
+ generate: \
+ 		genie \
+-		$(GEN_FOLDERS) \
+ 		$(GENDIR)/version.cpp \
+ 		$(patsubst %.po,%.mo,$(call rwildcard, language/, *.po)) \
+ 		$(patsubst $(SRC)/%.lay,$(GENDIR)/%.lh,$(LAYOUTS)) \
+ 		$(GENDIR)/mame/machine/mulcd.hxx \
+-		$(GENDIR)/includes/SDL2
++		$(GENDIR)/includes/SDL2 | $(GEN_FOLDERS)
+ 
+ $(GENDIR)/includes/SDL2:
+ 	-$(call MKDIR,$@)
+@@ -1754,7 +1753,7 @@
+ 	@echo Compressing $<...
+ 	$(SILENT)$(PYTHON) scripts/build/complay.py $< $@ layout_$(basename $(notdir $<))
+ 
+-$(GENDIR)/mame/machine/mulcd.hxx: $(SRC)/mame/machine/mulcd.ppm scripts/build/file2str.py
++$(GENDIR)/mame/machine/mulcd.hxx: $(SRC)/mame/machine/mulcd.ppm scripts/build/file2str.py | $(GEN_FOLDERS)
+ 	@echo Converting $<...
+ 	$(SILENT)$(PYTHON) scripts/build/file2str.py $< $@ mulcd_bkg uint8_t
+ 
 --- a/3rdparty/genie/src/actions/make/make_cpp.lua	2020-01-09 10:56:49.931595408 +0100
 +++ b/3rdparty/genie/src/actions/make/make_cpp.lua	2020-01-09 10:59:04.237732440 +0100
 @@ -560,7 +560,7 @@