build: Remove --with-virt-v2v-nbdkit-python-plugin=...

In theory, ./configure --with-virt-v2v-nbdkit-python-plugin=<name>
allowed you to override the default nbdkit-python-plugin name (usually
"python").  However:

 (a) nbdkit no longer provides a Python version 2 plugin and hasn't
 since nbdkit 1.16 (2019),

 (b) we no longer support older RHEL where there were parallel Python
 2 & 3 plugins and this was an issue, and

 (c) the result wasn't actually used in the code (it used to be, but I
 think I replaced it with "python" and forgot about this ./configure
 parameter).

config.sh.in

@@ -19,5 +19,4 @@
 # This shell script contains the results of some configure checks,
 # mostly used in other shell scripts.
 
-export VIRT_V2V_NBDKIT_PYTHON_PLUGIN="@VIRT_V2V_NBDKIT_PYTHON_PLUGIN@"
 export PYCODESTYLE="@PYCODESTYLE@"

configure.ac

@@ -97,10 +97,6 @@ dnl Perl, used for running mllibvirt generator, and man pages.
 HEADING([Checking for Perl])
 m4_include([m4/guestfs-perl.m4])
 
-dnl virt-v2v.
-HEADING([Checking the virt-v2v dependencies])
-m4_include([m4/guestfs-v2v.m4])
-
 dnl Bash completion.
 HEADING([Checking for bash completion])
 m4_include([m4/guestfs-bash-completion.m4])

lib/config.ml.in

@@ -23,4 +23,3 @@ let package_version_full = "@PACKAGE_VERSION_FULL@"
 let prefix = "@prefix@"
 let datadir = prefix ^ "/share"
 let host_cpu = "@host_cpu@"
-let nbdkit_python_plugin = "@VIRT_V2V_NBDKIT_PYTHON_PLUGIN@"

lib/config.mli

@@ -33,12 +33,3 @@ val datadir : string
 
 val host_cpu : string
 (** The configure value [@host_cpu@] *)
-
-val nbdkit_python_plugin : string
-(** Return the name of the nbdkit python plugin used by
-    [virt-v2v -o rhv-upload].
-
-    As above this must also be the Python 3 version of the plugin,
-    unless you change it.  The configure command to change this is:
-
-    [./configure --with-virt-v2v-nbdkit-python-plugin=...] *)

tests/test-v2v-o-rhv-upload.sh

@@ -31,7 +31,7 @@ set -x
 
 skip_if_skipped
 requires python3 --version
-requires nbdkit $VIRT_V2V_NBDKIT_PYTHON_PLUGIN --version
+requires nbdkit python --version
 requires test -f ../test-data/phony-guests/windows.img
 
 libvirt_uri="test://$abs_top_builddir/test-data/phony-guests/guests.xml"