rules: Introduce ARCHES_QEMU

The QEMU package only builds the system emulators on certain
architectures, with some being explicitly left out.

For those (currently alpha, hppa, ia64, m68k and sh4) it
doesn't make sense for us to try and build the QEMU driver,
as the system emulators are a requirement for it to be of
any use at all.

This should make libvirt buildable on those architectures,
or at the very least get us closer to that goal.

debian/control

@@ -57,7 +57,7 @@ Build-Depends:
  po-debconf,
  python3-docutils,
  python3:native,
- qemu-utils,
+ qemu-utils [amd64 arm64 armel armhf i386 mips64el mipsel powerpc ppc64 ppc64el riscv64 s390x sparc64 x32],
  systemtap-sdt-dev [linux-any],
  xsltproc,
 Vcs-Git: https://salsa.debian.org/libvirt-team/libvirt.git
@@ -177,7 +177,7 @@ Description: Virtualization daemon
 
 Package: libvirt-daemon-driver-qemu
 Section: admin
-Architecture: linux-any
+Architecture: amd64 arm64 armel armhf i386 mips64el mipsel powerpc ppc64 ppc64el riscv64 s390x sparc64 x32
 Multi-Arch: no
 Depends:
  libvirt0 (= ${binary:Version}),

debian/rules

@@ -18,11 +18,17 @@ export DPKG_GENSYMBOLS_CHECK_LEVEL
 
 ARCHES_CEPH = amd64 arm64 armel armhf i386 mips64el mipsel powerpc ppc64el riscv64 s390x
 ARCHES_GLUSTER = amd64 arm64 ia64 mips64el ppc64 ppc64el riscv64 s390x sparc64
+ARCHES_QEMU = amd64 arm64 armel armhf i386 mips64el mipsel powerpc ppc64 ppc64el riscv64 s390x sparc64 x32
 ARCHES_LXC  = alpha amd64 arm64 armel armhf hppa i386 m68k mips64el mipsel powerpc ppc64 ppc64el riscv64 s390x sh4 sparc64 x32
 ARCHES_XEN  = amd64 arm64 armhf
 ARCHES_VBOX = amd64 i386
 
 ifeq ($(DEB_HOST_ARCH_OS), linux)
+    ifneq (,$(filter $(DEB_HOST_ARCH), $(ARCHES_QEMU)))
+        WITH_QEMU             = -Ddriver_qemu=enabled
+    else
+        WITH_QEMU             = -Ddriver_qemu=disabled
+    endif
     ifneq (,$(filter $(DEB_HOST_ARCH), $(ARCHES_VBOX)))
         WITH_VBOX             = -Ddriver_vbox=enabled
     else
@@ -71,6 +77,7 @@ ifeq ($(DEB_HOST_ARCH_OS), linux)
         WITH_LOGIN_SHELL      = -Dlogin_shell=disabled
     endif
 else
+    WITH_QEMU                 = -Ddriver_qemu=disabled
     WITH_VBOX                 = -Ddriver_vbox=disabled
     WITH_LIBXL                = -Ddriver_libxl=disabled
     WITH_STORAGE_LVM          = -Dstorage_lvm=disabled
@@ -105,7 +112,7 @@ DEB_CONFIGURE_EXTRA_ARGS := \
     -Dinitconfdir=/etc/default \
     -Dpackager="$(DEB_VENDOR)" \
     -Dpackager_version="$(DEB_VERSION)" \
-    -Ddriver_qemu=enabled \
+    $(WITH_QEMU) \
     -Ddriver_libvirtd=enabled \
     -Ddriver_remote=enabled \
     -Dremote_default_mode=legacy \