toolchain/53178: Building GCC blows up macOS 10.13.4 clang - need to increase max bracket depth

[thorpej%me.com@localhost]

>Number:         53178
>Category:       toolchain
>Synopsis:       Building GCC blows up macOS 10.13.4 clang - need to increase max bracket depth
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 13 04:20:00 +0000 2018
>Originator:     Jason Thorpe
>Release:        NetBSD 8.99.14
>Organization:
>Environment:
NetBSD nixie-dev 8.99.14 NetBSD 8.99.14 (thorpej-RPI-NixieClock) #9: Mon Apr  9 21:09:00 PDT 2018 thorpej@BigMac.local:/Volumes/Data0/Users/thorpej/hack/NetBSD/current/src/sys/arch/evbarm/compile/thorpej-RPI-NixieClock evbarm
>Description:
When building on a macOS 10.13.4 host, building the cross GCC for ARM blows up because the neon module makes llvm on the host cranky by exceeding max bracket depth.
>How-To-Repeat:
Attempt to build earmv6hf host tools on macOS.
>Fix:
Index: tools/Makefile.gnuhost
===================================================================
RCS file: /cvsroot/src/tools/Makefile.gnuhost,v
retrieving revision 1.44
diff -u -p -r1.44 Makefile.gnuhost
--- tools/Makefile.gnuhost	16 Jan 2016 18:38:53 -0000	1.44
+++ tools/Makefile.gnuhost	13 Apr 2018 04:18:11 -0000
@@ -20,7 +20,8 @@
 # Disable use of pre-compiled headers on Darwin.
 BUILD_OSTYPE!= uname -s
 .if ${BUILD_OSTYPE} == "Darwin"
-HOST_CFLAGS+=-O2 -no-cpp-precomp
+HOST_CFLAGS+=-O2 -no-cpp-precomp -fbracket-depth=512
+HOST_CXXFLAGS+= -fbracket-depth=512
 .endif
 MAKE_PROGRAM?=	${MAKE}