dns/dnsmasq-devel: update to v2.92test21

Upstream changes by Simon Kelley:
* 1e83316 2025-08-21 | Formatting. (tag: v2.92test21)
* 9a566c0 2025-08-21 | Tweak recently altered TFTP code.
* 06e2d47 2025-08-21 | Stop lookup_frec() returning old records.
* b52d1d2 2025-08-21 | Tweak get_new_frec() behaviour in "force" mode.
* 18195e7 2025-08-21 | Useful error logging in dhcp-split-relay code.
* d81b1d7 2025-08-21 | Fix TFTP problems with large files.
* 1677c6e 2025-08-20 | More development on dhcp-split-relay. (tag: v2.92test20)

MFH:		2025Q3

dns/dnsmasq-devel/Makefile

@@ -1,5 +1,5 @@
 PORTNAME=	dnsmasq
-DISTVERSION=	2.92test19 # remember to bump PORTEPOCH when going from test to rc!
+DISTVERSION=	2.92test21 # remember to bump PORTEPOCH when going from test to rc!
 # Leave the PORTREVISION in even if 0 to avoid accidental PORTEPOCH bumps:
 PORTREVISION=	0
 PORTEPOCH=	6

dns/dnsmasq-devel/distinfo

@@ -1,3 +1,3 @@
-TIMESTAMP = 1754979310
-SHA256 (dnsmasq-2.92test19.tar.xz) = cb2ba3d8594a01896349959c3341fad253f0434efe51df3aa0cd8a0ca385f823
-SIZE (dnsmasq-2.92test19.tar.xz) = 584612
+TIMESTAMP = 1756306668
+SHA256 (dnsmasq-2.92test21.tar.xz) = bb755e2cc891e05446b2a16b6f2f66ecd1c3e43e6bc0861ef3b60e088848c419
+SIZE (dnsmasq-2.92test21.tar.xz) = 585408