toolchain/56269: ./build.sh tools does not work on Apple M1 Macs due to GMP library

[chris_pinnock%mac.com@localhost]

>Number:         56269
>Category:       toolchain
>Synopsis:       ./build.sh tools does not work on Apple M1 Macs due to GMP library
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 22 17:20:00 +0000 2021
>Originator:     Chris Pinnock
>Release:        NetBSD-current sources today
>Organization:
Limited
>Environment:
chris@Tez% uname -a
Darwin Tez 20.5.0 Darwin Kernel Version 20.5.0: Sat May  8 05:10:31 PDT 2021; root:xnu-7195.121.3~9/RELEASE_ARM64_T8101 arm64
Apple clang version 12.0.5 (clang-1205.0.22.9)
Target: arm64-apple-darwin20.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin


>Description:

The GMP library fails to build during the toolchain build:
checking size of mp_limb_t... 8
configure: error: Oops, mp_limb_t is 64 bits, but the assembler code
in this configuration expects 32 bits.
>How-To-Repeat:

Get an Apple Mac with M1 chip.
Download NetBSD srcs
./build.sh -m amd64 -U tools
>Fix:
GMP 6.2.1 has better support for Darwin/Mac M1 systems and configures and builds from mainline. At some point we will update our in-tree GMP.

(Adding --disable-assembly to ./configure will get GMP 6.2.0 to build but might not give the right results.)