bug#37759: network-manager-openvpn broken since network-manager-applet update

[Jelle Licht]

Commit 8fc3a337ab420dc9f80472ce057eae603fc892d3, the update of
network-manager-applet to 1.8.24, broke network-manager-openvpn:

--8<---------------cut here---------------start------------->8---
checking for LIBNM_GTK... no
configure: error: Package requirements (libnm-gtk >= 1.7.0) were not met:

No package 'libnm-gtk' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables LIBNM_GTK_CFLAGS
and LIBNM_GTK_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
command 
"/gnu/store/29jhbbg1hf557x8j53f9sxd9imlmf02a-bash-minimal-5.0.7/bin/bash" 
"./configure" 
"CONFIG_SHELL=/gnu/store/29jhbbg1hf557x8j53f9sxd9imlmf02a-bash-minimal-5.0.7/bin/bash"
 
"SHELL=/gnu/store/29jhbbg1hf557x8j53f9sxd9imlmf02a-bash-minimal-5.0.7/bin/bash" 
"--prefix=/gnu/store/0rgybwyxiy7b74byqr3ld303l7iy99jx-network-manager-openvpn-1.8.4"
 "--enable-fast-install" "--build=x86_64-unknown-linux-gnu" 
"--enable-absolute-paths" "--localstatedir=/var" failed with status 1
builder for 
`/gnu/store/jbbzxdd8jqjdp7hj1jskd09cyggrrl0k-network-manager-openvpn-1.8.4.drv' 
failed with exit code 1
--8<---------------cut here---------------end--------------->8---

I already verified that updating network-manager-openvpn to the latest
release (1.8.10) does not fix this issue.