modemmanager: fix build

We did not notice it was creating directories in /etc in sandbox due to Nix 2.12 regression.

pkgs/tools/networking/modemmanager/default.nix

@@ -33,6 +33,12 @@ stdenv.mkDerivation rec {
     hash = "sha256-OWP23EQ7a8rghhV7AC9yinCxRI0xwcntB5dl9XtgK6M=";
   };
 
+  patches = [
+    # Since /etc is the domain of NixOS, not Nix, we cannot install files there.
+    # But these are just placeholders so we do not need to install them at all.
+    ./no-dummy-dirs-in-sysconfdir.patch
+  ];
+
   nativeBuildInputs = [
     meson
     ninja
@@ -64,6 +70,7 @@ stdenv.mkDerivation rec {
 
   mesonFlags = [
     "-Dudevdir=${placeholder "out"}/lib/udev"
+    "-Ddbus_policy_dir=${placeholder "out"}/share/dbus-1/system.d"
     "--sysconfdir=/etc"
     "--localstatedir=/var"
     "-Dvapi=true"

pkgs/tools/networking/modemmanager/no-dummy-dirs-in-sysconfdir.patch

@@ -0,0 +1,20 @@
+diff --git a/data/dispatcher-connection/meson.build b/data/dispatcher-connection/meson.build
+index 2e7ef8b4..e0f4aa66 100644
+--- a/data/dispatcher-connection/meson.build
++++ b/data/dispatcher-connection/meson.build
+@@ -21,5 +21,4 @@ install_data(
+ )
+ 
+ mkdir_cmd = 'mkdir -p ${DESTDIR}@0@'
+-meson.add_install_script('sh', '-c', mkdir_cmd.format(mm_prefix / mm_connectiondiruser))
+ meson.add_install_script('sh', '-c', mkdir_cmd.format(mm_prefix / mm_connectiondirpackage))
+diff --git a/data/dispatcher-fcc-unlock/meson.build b/data/dispatcher-fcc-unlock/meson.build
+index 5dc3b6a0..25a948a1 100644
+--- a/data/dispatcher-fcc-unlock/meson.build
++++ b/data/dispatcher-fcc-unlock/meson.build
+@@ -39,5 +39,4 @@ foreach output, input: vidpids
+ endforeach
+ 
+ mkdir_cmd = 'mkdir -p ${DESTDIR}@0@'
+-meson.add_install_script('sh', '-c', mkdir_cmd.format(mm_prefix / mm_fccunlockdiruser))
+ meson.add_install_script('sh', '-c', mkdir_cmd.format(mm_prefix / mm_fccunlockdirpackage))