BUG/MINOR: mworker: stop doing strtok directly from the env

When parsing the HAPROXY_PROCESSES environement variable, strtok was
done directly from the ptr resulting from getenv(), which replaces the ;
by \0, showing confusing environment variables when debugging in /proc
or in a corefile.

Example:

	(gdb) x/39s *environ
	[...]
	0x7fff6935af64: "HAPROXY_PROCESSES=|type=w"
	0x7fff6935af7e: "fd=3"
	0x7fff6935af83: "pid=4444"
	0x7fff6935af8d: "rpid=1"
	0x7fff6935af94: "reloads=0"
	0x7fff6935af9e: "timestamp=1676338060"
	0x7fff6935afb3: "id="
	0x7fff6935afb7: "version=2.4.0-8076da-1010+11"

This patch fixes the issue by doing a strdup on the variable.

Could be backported in previous versions (mworker_proc_to_env_list
exists since 1.9)
diff --git a/src/mworker.c b/src/mworker.c
index 4bc224e..0d788ca 100644
--- a/src/mworker.c
+++ b/src/mworker.c
@@ -166,17 +166,26 @@
 
 /*
  * unserialize the proc list from the environment
+ * Return < 0 upon error.
  */
 int mworker_env_to_proc_list()
 {
-	char *msg, *token = NULL, *s1;
+	char *env, *msg, *omsg = NULL, *token = NULL, *s1;
 	struct mworker_proc *child;
 	int minreloads = INT_MAX; /* minimum number of reloads to chose which processes are "current" ones */
+	int err = 0;
 
-	msg = getenv("HAPROXY_PROCESSES");
-	if (!msg)
+	env = getenv("HAPROXY_PROCESSES");
+	if (!env)
 		return 0;
 
+	omsg = msg = strdup(env);
+	if (!msg) {
+		ha_alert("Out of memory while trying to allocate a worker process structure.");
+		err = -1;
+		goto out;
+	}
+
 	while ((token = strtok_r(msg, "|", &s1))) {
 		char *subtoken = NULL;
 		char *s2;
@@ -185,8 +194,9 @@
 
 		child = mworker_proc_new();
 		if (!child) {
-			ha_alert("Out of memory while trying to allocate a worker process structure.");
-			return -1;
+			ha_alert("out of memory while trying to allocate a worker process structure.");
+			err = -1;
+			goto out;
 		}
 
 		while ((subtoken = strtok_r(token, ";", &s2))) {
@@ -244,7 +254,9 @@
 
 	unsetenv("HAPROXY_PROCESSES");
 
-	return 0;
+out:
+	free(omsg);
+	return err;
 }
 
 /* Signal blocking and unblocking */