semihosting: clean up handling of expanded argv

Another cleanup patch tripped over the fact we weren't being careful
in our casting. Fix the casts, allow for a non-const and switch from
g_realloc to g_renew.

The whole semihosting argument handling could do with some tests
though.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220315121251.2280317-8-alex.bennee@linaro.org>

semihosting/config.c

@@ -51,7 +51,7 @@ typedef struct SemihostingConfig {
     bool enabled;
     SemihostingTarget target;
     Chardev *chardev;
-    const char **argv;
+    char **argv;
     int argc;
     const char *cmdline; /* concatenated argv */
 } SemihostingConfig;
@@ -98,8 +98,8 @@ static int add_semihosting_arg(void *opaque,
     if (strcmp(name, "arg") == 0) {
         s->argc++;
         /* one extra element as g_strjoinv() expects NULL-terminated array */
-        s->argv = g_realloc(s->argv, (s->argc + 1) * sizeof(void *));
-        s->argv[s->argc - 1] = val;
+        s->argv = g_renew(char *, s->argv, s->argc + 1);
+        s->argv[s->argc - 1] = g_strdup(val);
         s->argv[s->argc] = NULL;
     }
     return 0;