meta-networking: Drop broken BBCLASSEXTEND variants

The command "bitbake universe -c fetch" currently throws a ton of warnings
as there are many 'impossible' dependencies.

In some cases these variants may never have worked and were just added by copy
and paste of recipes. In some cases they once clearly did work but became
broken somewhere along the way. Users may also be carrying local bbappend files
which add further BBCLASSEXTEND.

Having universe fetch work without warnings is desireable so clean up the broken
variants. Anyone actually needing something dropped here can propose adding it
and the correct functional dependencies back quite easily. This also then
ensures we're not carrying or fixing things nobody uses.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
(cherry picked from commit e1b332f2eff7df2336ff87917cd48249edf763a2)
Backport: Adapted modified recipes to the ones generating warnings
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-networking/recipes-connectivity/mosquitto/mosquitto_2.0.18.bb

@@ -89,4 +89,4 @@ USERADD_PACKAGES = "${PN}"
 USERADD_PARAM:${PN} = "--system --no-create-home --shell /bin/false \
                        --user-group mosquitto"
 
-BBCLASSEXTEND += "native nativesdk"
+BBCLASSEXTEND = "native"

meta-networking/recipes-support/netsniff-ng/netsniff-ng_0.6.8.bb

@@ -33,4 +33,4 @@ do_install() {
     oe_runmake DESTDIR=${D} netsniff-ng_install
 }
 
-BBCLASSEXTEND = "native nativesdk"
+BBCLASSEXTEND = "native"