Fix use-after-free warning (fixes #273)

Author: evanmiller

src/sas/readstat_sas7bdat_read.c

@@ -703,7 +703,6 @@ static readstat_variable_t *sas7bdat_init_variable(sas7bdat_ctx_t *ctx, int i,
 
 cleanup:
     if (retval != READSTAT_OK) {
-        free(variable);
         if (out_retval)
             *out_retval = retval;
 
@@ -716,6 +715,8 @@ static readstat_variable_t *sas7bdat_init_variable(sas7bdat_ctx_t *ctx, int i,
             }
         }
 
+        free(variable);
+
         return NULL;
     }