package/qemu: use a system-wide slirp

Use a system-wide slirp now that we switched to the up to date
https://gitlab.freedesktop.org/slirp/libslirp

qemu already depends on libglib2 so we don't need to add any new
dependencies

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/qemu/Config.in

@@ -58,6 +58,7 @@ comment "Networking options"
 
 config BR2_PACKAGE_QEMU_SLIRP
 	bool "Enable user mode networking (SLIRP)"
+	select BR2_PACKAGE_SLIRP
 	help
 	  Enable user mode network stack, which is the default
 	  networking backend. It requires no administrator privileges

package/qemu/qemu.mk

@@ -51,8 +51,10 @@ endif
 
 endif
 
-# There is no "--enable-slirp"
-ifeq ($(BR2_PACKAGE_QEMU_SLIRP),)
+ifeq ($(BR2_PACKAGE_QEMU_SLIRP),y)
+QEMU_OPTS += --enable-slirp=system
+QEMU_DEPENDENCIES += slirp
+else
 QEMU_OPTS += --disable-slirp
 endif