perf dso: Fix build when libunwind is enabled

Now that symsrc_filename is always accessed through an accessor, we also
need a free() function for it to avoid the following compilation error:

util/unwind-libunwind-local.c:416:12: error: lvalue required as unary
‘&’ operand
416 | zfree(&dso__symsrc_filename(dso));

Fixes: 1553419c3c10 ("perf dso: Fix address sanitizer build")
Signed-off-by: James Clark <[e-mail]>
Reviewed-by: Ian Rogers <[e-mail]>
Tested-by: Leo Yan <[e-mail]>
Tested-by: Florian Fainelli <[e-mail]>
Cc: Yunseong Kim <[e-mail]>
Cc: Athira Rajeev <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/dso.c

···
 	auxtrace_cache__free(RC_CHK_ACCESS(dso)->auxtrace_cache);
 	dso_cache__free(dso);
 	dso__free_a2l(dso);
-	zfree(&RC_CHK_ACCESS(dso)->symsrc_filename);
+	dso__free_symsrc_filename(dso);
 	nsinfo__zput(RC_CHK_ACCESS(dso)->nsinfo);
 	mutex_destroy(dso__lock(dso));
 	RC_CHK_FREE(dso);

tools/perf/util/dso.h

···
 	RC_CHK_ACCESS(dso)->symsrc_filename = val;
 }
 
+static inline void dso__free_symsrc_filename(struct dso *dso)
+{
+	zfree(&RC_CHK_ACCESS(dso)->symsrc_filename);
+}
+
 static inline enum dso_binary_type dso__symtab_type(const struct dso *dso)
 {
 	return RC_CHK_ACCESS(dso)->symtab_type;

tools/perf/util/unwind-libunwind-local.c

···
 							__func__,
 							dso__symsrc_filename(dso),
 							debuglink);
-					zfree(&dso__symsrc_filename(dso));
+					dso__free_symsrc_filename(dso);
 				}
 				dso__set_symsrc_filename(dso, debuglink);
 			} else {