Introduce pc repository for PC board support

Fix genodelabs/genode#4415

repos/README

@@ -103,6 +103,10 @@ but build upon of each other:
   The repository contains a server that uses a rump kernel to provide
   various NetBSD file systems to Genode.
 
+:'pc':
+  This source-code repository hosts device drivers that are specific for PC
+  platforms. It depends on the 'dde_linux' repository.
+
 :'ports':
 
   This source-code repository hosts ports of 3rd-party applications to

repos/pc/README

@@ -0,0 +1,20 @@
+
+               ================================
+               Genode support for x86-based PCs
+               ================================
+
+
+This repository complements the Genode OS framework (https://genode.org) with
+the board support needed to use Genode on devices based on x86 PCs.
+
+License
+-------
+
+Genode-specific code is provided under Genode's regular open-source license,
+which is AGPLv3 + open-source linking exception. This code is also available
+under a commercial license offered by Genode Labs.
+
+For code ported from other projects - e.g., device drivers ported from the
+Linux kernel - the license of the originating upstream project applies.
+
+Please refer to the individual file headers for detailed information.

tool/builddir/build.conf/repos_x86

@@ -1,3 +1,8 @@
+#
+# Drivers for x86 PC
+#
+#REPOSITORIES += $(GENODE_DIR)/repos/pc
+
 #
 # Drivers ported from the OpenBSD
 #