configure: move non-command-line variables away from command-line parsing section

This makes it easier to identify candidates for moving to Meson.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -307,16 +307,12 @@ debug="no"
 sanitizers="no"
 tsan="no"
 fortify_source="$default_feature"
-mingw32="no"
 gcov="no"
 EXESUF=""
 modules="no"
 module_upgrades="no"
 prefix="/usr/local"
 qemu_suffix="qemu"
-bsd="no"
-linux="no"
-solaris="no"
 profiler="no"
 softmmu="yes"
 linux_user=""
@@ -330,8 +326,6 @@ opengl="$default_feature"
 cpuid_h="no"
 avx2_opt="$default_feature"
 guest_agent="$default_feature"
-guest_agent_with_vss="no"
-guest_agent_ntddscsi="no"
 vss_win32_sdk="$default_feature"
 win_sdk="no"
 want_tools="$default_feature"
@@ -526,6 +520,10 @@ fi
 
 # OS specific
 
+mingw32="no"
+bsd="no"
+linux="no"
+solaris="no"
 case $targetos in
 windows)
   mingw32="yes"
@@ -2549,6 +2547,7 @@ fi
 ##########################################
 # check if we have VSS SDK headers for win
 
+guest_agent_with_vss="no"
 if test "$mingw32" = "yes" && test "$guest_agent" != "no" && \
         test "$vss_win32_sdk" != "no" ; then
   case "$vss_win32_sdk" in
@@ -2579,7 +2578,6 @@ EOF
       echo "ERROR: The headers are extracted in the directory \`inc'."
       feature_not_found "VSS support"
     fi
-    guest_agent_with_vss="no"
   fi
 fi
 
@@ -2606,6 +2604,7 @@ fi
 
 ##########################################
 # check if mingw environment provides a recent ntddscsi.h
+guest_agent_ntddscsi="no"
 if test "$mingw32" = "yes" && test "$guest_agent" != "no"; then
   cat > $TMPC << EOF
 #include <windows.h>