BUG/MEDIUM: h3: fix BUG_ON() crash with glitch on SETTINGS parsing

BUG/MEDIUM: h3: fix BUG_ON() crash with glitch on SETTINGS parsing

There is a risk of BUG_ON() crash when glitch are reported via
qcc_report_glitch() before settings a connection-level error using
qcc_set_error(). This happens when reaching the glitch level with the
former function also calling qcc_set_error(). A BUG_ON() is triggered as
it must not be called multiple times per connection to prevent error
code erasure.

This patch fixes glitch reporting during SETTINGS frame parsing. Now,
qcc_report_glitch() is only called after qcc_set_error() on
h3_parse_settings_frm() return.

This must be backported up to 3.0.