configure, meson: move Spice configure handling to meson

Add meson feature options for Spice and Spice protocol, and move
detection logic out of configure.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20211007102453.978041-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20211007130829.632254-13-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/chardev/meson.build b/chardev/meson.build
index 32377af..325ba2b 100644
--- a/chardev/meson.build
+++ b/chardev/meson.build
@@ -35,7 +35,7 @@
   chardev_modules += { 'baum': module_ss }
 endif
 
-if config_host.has_key('CONFIG_SPICE')
+if spice.found()
   module_ss = ss.source_set()
   module_ss.add(when: [spice], if_true: files('spice.c'))
   chardev_modules += { 'spice': module_ss }