grub: disable rpath, fix linking under Darwin

package/grub/Makefile

@@ -101,11 +101,13 @@ HOST_CONFIGURE_ARGS+=	--enable-efiemu=no \
 			--disable-grub-mkfont \
 			--enable-device-mapper=no \
 			--enable-libzfs=no \
+			--disable-rpath \
 			--disable-werror
 CONFIGURE_ARGS+=	--disable-grub-mkfont \
 			--enable-efiemu=no \
 			--enable-device-mapper=no \
 			--enable-libzfs=no \
+			--disable-rpath \
 			--with-platform=$(GRUB_PLATFORM) \
 			--disable-werror
 

package/grub/patches/patch-grub-core_Makefile_am

@@ -0,0 +1,10 @@
+--- grub-07662af7aed55bcec448bc2a6610de1f0cb62100.orig/grub-core/Makefile.am	2017-02-12 20:56:32.000000000 +0100
++++ grub-07662af7aed55bcec448bc2a6610de1f0cb62100/grub-core/Makefile.am	2017-03-28 08:00:46.000000000 +0200
+@@ -61,6 +61,7 @@ grub_script.yy.c: grub_script.yy.h
+ 
+ rs_decoder.h: $(srcdir)/lib/reed_solomon.c
+ 	$(TARGET_CC) $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) -Os -I$(top_builddir) -S -DSTANDALONE -o $@ $< -g0 -mregparm=3 -ffreestanding
++	sed -i -e "s#.*macosx_version_min.*##" $@
+ 
+ CLEANFILES += grub_script.yy.c grub_script.yy.h
+