Yes.
any github commit can be downloaded just by adding ".patch" to the and of it. Download it with wget,curl or ...whatever, then just apply the patch.
web page: https://github.com/dissent1/r7800/commit/fd065e652c2d49db3fab42f800ff9002ce4993fa
patch: https://github.com/dissent1/r7800/commit/fd065e652c2d49db3fab42f800ff9002ce4993fa.patch
You can first test it with "dry-run" quite normally, so that you see that it applies without errors. (run patch command from buildroot root)
patch --dry-run -p 1 -i patchname
(And I think that original for that is actually in blogic's staging tree (but dissent's version might have additional fixes, I haven't checked)
https://git.lede-project.org/?p=lede/blogic/staging.git;a=shortlog;h=refs/heads/qca8k
Yeah, you should take this kind of generic discussion to the R7800 exploration thread Netgear R7800 exploration (IPQ8065, QCA9984) (if the topic is R7800- or ipq806x-specific), or even better, start a new thread about IGMP snooping.
Two main reasons: this off-topic discussion clutters this topic, and even worse, you don't reach the attention of people who really know about IGMP snooping (as they likely are not interested in my R7800 build).