db_perlvdb: fix valdata inline

Thanks go to @varghesepaul for reporting it
Close #3152

(cherry picked from commit 8b2ac92)

modules/db_perlvdb/perlvdb_conv.c

@@ -91,7 +91,7 @@ AV *keys2perlarray(db_key_t* keys, int n) {
 	return array;
 }
 
-inline SV *valdata(db_val_t* val) {
+static inline SV *valdata(db_val_t* val) {
 	SV *data = &PL_sv_undef;
 	const char* stringval;