Guix shell doesn't work properly if guile-3.0 executable is on host system

Here's an example of this happening:

$ ./configure
checking for a BSD-compatible install... /gnu/store/w7ag4ilvb6inp9vc71dxzmdkz738m37w-profile/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /gnu/store/w7ag4ilvb6inp9vc71dxzmdkz738m37w-profile/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
checking whether make supports nested variables... (cached) yes
checking for pkg-config... /gnu/store/w7ag4ilvb6inp9vc71dxzmdkz738m37w-profile/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
configure: checking for guile 3.0
configure: found guile 3.0
checking for guile-3.0... /usr/bin/guile-3.0
checking for Guile version >= 3.0... 3.0.7
checking for guild-3.0... /gnu/store/w7ag4ilvb6inp9vc71dxzmdkz738m37w-profile/bin/guild
checking for guile-config-3.0... no
checking for Guile site directory... /gnu/store/cnfsv9ywaacyafkqdqsv2ry8f01yr7a9-guile-3.0.7/share/guile/site/3.0
checking for Guile site-ccache directory using pkgconfig... /gnu/store/cnfsv9ywaacyafkqdqsv2ry8f01yr7a9-guile-3.0.7/lib/guile/3.0/site-ccache
checking for Guile extensions directory... /gnu/store/cnfsv9ywaacyafkqdqsv2ry8f01yr7a9-guile-3.0.7/lib/guile/3.0/extensions
checking if (fibers) is available... no
configure: error: required guile module not found: (fibers)

Note checking for guile-3.0... /usr/bin/guile-3.0. This is because Guix's Guile package doesn't have a guile-3.0 executable. We should see if there's a way to tweak how Guile's autoconf script works so it doesn't even check for guile-3.0.