Use different catalystrc for stages 1 to 3.

catalystrc

@@ -0,0 +1,35 @@
+#!/bin/bash
+# This is an example catalystrc. As such, it doesn't actually *do* anything.
+
+# Uncomment the following to increase the number of threads used to compile.
+# export MAKEOPTS="-j16"
+
+#export EMERGE_DEFAULT_OPTS=-j8
+
+export BINPKG_COMPRESS="gzip"
+#export BINPKG_COMPRESS_FLAGS="-4"
+
+export SHELL=/bin/bash
+export PYTHON=python
+
+# We're going unstable
+export ACCEPT_KEYWORDS="~amd64"
+
+# Hardware flags
+export CPU_FLAGS_X86="aes mmx mmxext pclmul popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3"
+export ABI_X86="32 64"
+#export LLVM_TARGETS="X86"
+export VIDEO_CARDS="i915 i965 intel nouveau amdgpu radeon r600"
+export INPUT_DEVICES="evdev keyboard libinput mouse synaptics joystick"
+
+
+# Software environments.
+export PYTHON_TARGETS="python2_7 python3_6 python3_7"
+export PYTHON_SINGLE_TARGET="python3_6"
+export RUBY_TARGETS="ruby25"
+
+# Internationalization
+export L10N="en fr"
+
+#export USE="gold plugins"
+#export USE="-filecaps"