m_option: fix -vo opengl lscale validation

OPT_STRING_VALIDATE actually did nothing. This made -vo opengl crash or
misbehave when passing an invalid value for the lscale, cscale or 3dlut-
size (the only users for this option type).

The code added with this commit was either blatantly forgotten with the
commit introducing this option type, or somehow lost.

1 files changed, 7 insertions, 0 deletions

diff --git a/core/m_option.c b/core/m_option.c
index 931b498213..406e4ede0b 100644
--- a/core/m_option.c
+++ b/core/m_option.c
@@ -762,6 +762,13 @@ static int parse_str(const m_option_t *opt, struct bstr name,
         goto exit;
     }
 
+    m_opt_string_validate_fn validate = opt->priv;
+    if (validate) {
+        r = validate(opt, name, param);
+        if (r < 0)
+            goto exit;
+    }
+
     if (opt->flags & M_OPT_PARSE_ESCAPES) {
         char *res = unescape_string(tmp, param);
         if (!res) {