util/crossgcc: update to gcc 8.1.0 and binutils 2.30

Also update patches as necessary.

Change-Id: I1e8074954d5d7a4eff590abb7439e9be7d3762aa
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: https://review.coreboot.org/25997
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/crossgcc/patches/gcc-8.1.0_gnat.patch

@@ -0,0 +1,11 @@
+--- gcc-6.1.0/gcc/ada/gcc-interface/Make-lang.in.bak	2015-08-24 16:23:25.004493665 +0200
++++ gcc-6.1.0/gcc/ada/gcc-interface/Make-lang.in	2015-08-24 17:53:52.496636113 +0200
+@@ -45,7 +45,7 @@
+ 
+ 
+ # Extra flags to pass to recursive makes.
+-COMMON_ADAFLAGS= -gnatpg
++COMMON_ADAFLAGS= -gnatpg -gnatwGUR
+ ifeq ($(TREECHECKING),)
+ CHECKING_ADAFLAGS=
+ else