toolchain/59418: using the basename of the cloned source dirs breaks reproducible builds

[christos%netbsd.org@localhost]

>Number:         59418
>Category:       toolchain
>Synopsis:       using the basename of the cloned source dirs breaks reproducible builds
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue May 13 00:30:00 +0000 2025
>Originator:     Christos Zoulas
>Release:        NetBSD 10.99.14
>Organization:
	unreproducible builds inc.
>Environment:
System: NetBSD quasar.astron.com 10.99.14 NetBSD 10.99.14 (QUASAR) #50: Mon May 5 20:25:28 EDT 2025 christos%quasar.astron.com@localhost:/usr/src/sys/arch/amd64/compile/QUASAR amd64
Architecture: x86_64
Machine: amd64
>Description:
	Binaries should not contain inconsistent data that depends on the
	directory of the checked out code.
>How-To-Repeat:
	https://tests.reproducible-builds.org/netbsd/dbd/sparc64-sparc64/sparc64/binary/sets/base32.tgz.html
	see binaries containing: b1-sparc64-sparc64 vs b2-sparc64-sparc64
>Fix:
	Fix the names in build.sh to be always src and xsrc not the basename
	of the directory of the checkout.