Try building 9.0.1

Enable the compiler optimizations that were crashing qemu-user with LLVM
9 to see if the situation is improved with LLVM 10.

.gitlab-ci.yml

 ---
 variables:
-  VERSION: '8.10.3'
+  VERSION: '9.0.1'
 
 .template: &template
   image: '${CI_REGISTRY}/nest/stage1:${BUILD_CPU}-workstation'
@@ -10,7 +10,7 @@ variables:
     - 'emerge --sync'
     - 'MAKEOPTS="$CI_HOST_MAKEOPTS" emerge -v -j1 --onlydeps "=dev-lang/ghc-${VERSION}"'
     - 'BINPKG_COMPRESS=bzip2
-       CFLAGS=
+       CFLAGS="-O2 -pipe"
        FEATURES=-splitdebug
        MAKEOPTS="$CI_HOST_MAKEOPTS"
        PKGDIR=/tmp/packages
@@ -18,6 +18,12 @@ variables:
        ebuild "/var/db/repos/nest/dev-lang/ghc/ghc-${VERSION}.ebuild" package'
     - 'cp "/tmp/packages/dev-lang/ghc/ghc-${VERSION}-1.xpak" "/nest/portage/distfiles/ghc-bin-${VERSION}-${CHOST}.tbz2"'
 
+'Build amd64':
+  <<: *template
+  variables:
+    BUILD_CPU: 'haswell'
+    CHOST: 'x86_64-pc-linux-gnu'
+
 'Build arm64':
   <<: *template
   variables: