Create virtual packages for OpenPower toolchain

Create a "toolchain" category, plus "p8-pore-toolchain" and
"ppe42-toolchain" virtual-packages, with the goal of lowering the
coupling between these toolchain and target packages.

Signed-off-by: Klaus Heinrich Kiwi <klaus@linux.vnet.ibm.com>
diff --git a/openpower/package/sbe/Config.in b/openpower/package/sbe/Config.in
index 2291255..e5f1d46 100644
--- a/openpower/package/sbe/Config.in
+++ b/openpower/package/sbe/Config.in
@@ -3,6 +3,7 @@
         default y if (BR2_OPENPOWER_PLATFORM && BR2_OPENPOWER_POWER9)
         select BR2_CPP
         depends on BR2_PACKAGE_HCODE
+        depends on BR2_PACKAGE_HAS_PPE42_TOOLCHAIN
         help
             Project to build the sbe firmware codebase
 
diff --git a/openpower/package/sbe/sbe.mk b/openpower/package/sbe/sbe.mk
index 121e2c4..2f6d5b4 100644
--- a/openpower/package/sbe/sbe.mk
+++ b/openpower/package/sbe/sbe.mk
@@ -8,7 +8,7 @@
 SBE_SITE = $(call github,open-power,sbe,$(SBE_VERSION))
 
 SBE_LICENSE = Apache-2.0
-SBE_DEPENDENCIES = host-ppe42-gcc hcode
+SBE_DEPENDENCIES = host-ppe42-toolchain hcode
 
 SBE_INSTALL_IMAGES = YES
 SBE_INSTALL_TARGET = NO