redhat/spec: Add libxml2-devel dependency for selftests build

JIRA: https://issues.redhat.com/browse/RHEL-48593

Upstream status: RHEL-only

The BPF selftests build requires libxml2.

Signed-off-by: Viktor Malik <vmalik@redhat.com>

Author: viktormalik

redhat/kernel.spec.template

@@ -736,7 +736,7 @@ BuildRequires: clang llvm-devel fuse-devel
 %ifarch x86_64 riscv64
 BuildRequires: lld
 %endif
-BuildRequires: libcap-devel libcap-ng-devel rsync libmnl-devel
+BuildRequires: libcap-devel libcap-ng-devel rsync libmnl-devel libxml2-devel
 BuildRequires: numactl-devel
 %endif
 BuildConflicts: rhbuildsys(DiskFree) < 500Mb