Disabling OABI_COMPAT on ARM platforms.

Otherwise, systemd-logind fails to work because SECCOMP_FILTER cannot be
enabled with OABI_COMPAT set. We don't need OABI_COMPAT at all on ARM, I
guess.

With this change, the rpi kernel boots fine for raspberrypi2.

We discussed this change with Dezgeg.

pkgs/top-level/platforms.nix

@@ -86,6 +86,10 @@ rec {
         ZRAM m
         NETCONSOLE m
 
+        # Disable OABI to have seccomp_filter (required for systemd)
+        # https://github.com/raspberrypi/firmware/issues/651
+        OABI_COMPAT n
+
         # Fail to build
         DRM n
         SCSI_ADVANSYS n
@@ -187,6 +191,10 @@ rec {
 
         ZRAM m
 
+        # Disable OABI to have seccomp_filter (required for systemd)
+        # https://github.com/raspberrypi/firmware/issues/651
+        OABI_COMPAT n
+
         # Fail to build
         DRM n
         SCSI_ADVANSYS n
@@ -268,6 +276,10 @@ rec {
 
         ZRAM m
 
+        # Disable OABI to have seccomp_filter (required for systemd)
+        # https://github.com/raspberrypi/firmware/issues/651
+        OABI_COMPAT n
+
         # Fail to build
         DRM n
         SCSI_ADVANSYS n