Added slightly better memory management after using meson […] -Db_sanitize=address.

src/libexim-encrypt-dlfunc-decrypt-secretbox.c

@@ -7,10 +7,6 @@
 #include <stdbool.h>
 #include "common.c"
 
-/* A note on memory management: this code lacks calls to free() for every malloc()ed piece of memory. This is deliberate
- * as these processes are short-lived and calling free() right before an exit() seems kind of moot.
- */
-
 #define ENVVAR_PASSWORD_NAME "LIBEXIM_PASSWORD"
 
 void print_usage(char *progname) {
@@ -162,4 +158,7 @@ int main(int argc, char *argv[]) {
     } else {
         fprintf(stdout, "%s", (const char *) cleartext);
     }
+
+    free(cleartext);
+    exit(EXIT_SUCCESS);
 }