meson: plugins

For now link arguments end up in Makefile.target, they will move to the
right place soon.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/meson.build b/meson.build
index 5b1608d..fa47410 100644
--- a/meson.build
+++ b/meson.build
@@ -731,6 +731,7 @@
 subdir('replay')
 subdir('hw')
 subdir('accel')
+subdir('plugins')
 subdir('bsd-user')
 subdir('linux-user')
 
@@ -899,6 +900,10 @@
 
 # Other build targets
 
+if 'CONFIG_PLUGIN' in config_host
+  install_headers('include/qemu/qemu-plugin.h')
+endif
+
 if 'CONFIG_GUEST_AGENT' in config_host
   subdir('qga')
 endif