gdb/solib-rocm: remove one xfree Replace a manual xfree with unique_xmalloc_ptr. Change-Id: I12a20106545905f1a80d069fc0555812cc3d6680 Approved-By: Tom Tromey <tom@tromey.com> Approved-by: Lancelot Six <lancelot.six@amd.com> (amdgpu)