tests/docker/test-mingw and docs: Remove --with-sdlabi=2.0

Patchew currently reports failures with the mingw docker test - this
is due to --with-sdlabi=2.0 configure flag which does not exist anymore.
Remove this remainder from the docker test and the docs now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1549268743-18502-1-git-send-email-thuth@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/multiseat.txt

@@ -9,7 +9,7 @@ First you must compile qemu with a user interface supporting
 multihead/multiseat and input event routing.  Right now this
 list includes sdl2, gtk (both 2+3) and vnc:
 
-  ./configure --enable-sdl --with-sdlabi=2.0
+  ./configure --enable-sdl
 
 or
 

tests/docker/test-mingw

@@ -27,8 +27,7 @@ for prefix in x86_64-w64-mingw32- i686-w64-mingw32-; do
         --enable-curl \
         --enable-vnc \
         --enable-bzip2 \
-        --enable-guest-agent \
-        --with-sdlabi=2.0
+        --enable-guest-agent
     install_qemu
     make clean