deprecation: don't enable TCG plugins by default with TCI

The softmmu memory instrumentation test sees so many more accesses
than a normal translated host and its really not worth fixing up. Lets
deprecate this odd configuration and save on the CI cycles.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240916085400.1046925-3-alex.bennee@linaro.org>

configure

@@ -629,6 +629,9 @@ meson_option_parse() {
     exit 1
   fi
 }
+has_meson_option() {
+    test "${meson_options#*"$1"}" != "$meson_options"
+}
 
 meson_add_machine_file() {
   if test "$cross_compile" = "yes"; then
@@ -1048,8 +1051,12 @@ if test "$static" = "yes" ; then
   plugins="no"
 fi
 if test "$plugins" != "no" && test $host_bits -eq 64; then
-  plugins=yes
-  subdirs="$subdirs contrib/plugins"
+    if has_meson_option "-Dtcg_interpreter=true"; then
+        plugins="no"
+    else
+        plugins=yes
+        subdirs="$subdirs contrib/plugins"
+    fi
 fi
 
 cat > $TMPC << EOF

docs/about/deprecated.rst

@@ -196,6 +196,14 @@ benefits from having plenty of host memory it seems reasonable to
 encourage users to use 64 bit builds of QEMU for analysis work
 whatever targets they are instrumenting.
 
+TCG Plugin support not enabled by default with TCI (since 9.2)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+While the TCG interpreter can interpret the TCG ops used by plugins it
+is going to be so much slower it wouldn't make sense for any serious
+instrumentation. Due to implementation differences there will also be
+anomalies in things like memory instrumentation.
+
 System emulator CPUs
 --------------------