emulators/qemu: Fix missing LIB_DEPENDS

Add net/libslirp into LIB_DEPENDS, now required for making user
networking functional.

In qemu 7.2 release the slirp code has been moved out of the source
package and is enabled/disabled at the build time based on the
availability of the libslirp shared library. As such, it needs to be
added into LIB_DEPENDS to make this feature available in the quemu
package.

See
https://wiki.qemu.org/ChangeLog/7.2#Removal_of_the_.22slirp.22_submodule_.28affects_.22-netdev_user.22.29
for a reference.

PR:		269475
Reported by:	sobomax

emulators/qemu/Makefile

 PORTNAME=	qemu
 PORTVERSION=	7.2.0
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	emulators
 MASTER_SITES=	https://download.qemu.org/
 DIST_SUBDIR=	qemu/${PORTVERSION}
@@ -19,7 +19,8 @@ ONLY_FOR_ARCHS=	aarch64 amd64 i386 powerpc64 powerpc64le
 BUILD_DEPENDS=	bash:shells/bash
 .if ${FLAVOR:U} != tools && ${FLAVOR:U} != guestagent
 LIB_DEPENDS+=	libfdt.so:sysutils/dtc \
-		libzstd.so:archivers/zstd
+		libzstd.so:archivers/zstd \
+		libslirp.so:net/libslirp
 .endif
 .if (${FLAVOR:U} != nox11 && ${FLAVOR:U} != tools && ${FLAVOR:U} != guestagent)
 LIB_DEPENDS+=	libepoxy.so:graphics/libepoxy