toolchain/55081: build.sh installmodules doesn't create all required directories

[jmcneill%invisible.ca@localhost]

>Number:         55081
>Category:       toolchain
>Synopsis:       build.sh installmodules doesn't create all required directories
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 18 10:40:01 +0000 2020
>Originator:     Jared McNeill
>Release:        9.99.50
>Organization:
>Environment:
NetBSD nge 9.99.49 NetBSD 9.99.49 (GENERIC64) #0: Sun Mar 15 15:58:24 UTC 2020  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/evbarm/compile/GENERIC64 evbarm
>Description:
Running build.sh installmodules to an empty target directory does not create all required directories. sys/modules/xldscripts/Makefile attempts to install a file to ${target}/usr/libdata/ldscripts/ and fails:

#   install  /tmp/mod/usr/libdata/ldscripts/kmodule
/home/jmcneill/netbsd/cvs-src/obj/tooldir.NetBSD-9.99.49-evbarm/bin/aarch64--netbsd-install -U -M /tmp/mod/METALOG -D /tmp/mod -h sha256 -N /home/jmcneill/netbsd/cvs-src/etc -c -p -r  -o root  -g wheel  -m 444   kmodule /tmp/mod/usr/libdata/ldscripts/kmodule
aarch64--netbsd-install: /tmp/mod/usr/libdata/ldscripts/kmodule.inst.aD8ehP: mkstemp: No such file or directory

*** Failed target:  /tmp/mod/usr/libdata/ldscripts/kmodule
*** Failed command: /home/jmcneill/netbsd/cvs-src/obj/tooldir.NetBSD-9.99.49-evbarm/bin/aarch64--netbsd-install -U -M /tmp/mod/METALOG -D /tmp/mod -h sha256 -N /home/jmcneill/netbsd/cvs-src/etc -c -p -r -o root -g wheel -m 444 kmodule /tmp/mod/usr/libdata/ldscripts/kmodule
*** Error code 1
>How-To-Repeat:
$ mkdir /tmp/mod
$ ./build.sh -U -m evbarm64 -j4 installmodules=/tmp/mod
>Fix: