configure: add --disable-tcg configure option

This lets you build without TCG (hardware accelerationor qtest only). When
this flag is passed to configure, it will automatically filter out the target
list to only those that support KVM or Xen or HAX.

Backports commit b3f6ea7e55e8228d6f84d5cee7cb11cae917ba95 from qemu

qemu/configure

@@ -174,6 +174,7 @@ solaris="no"
 softmmu="yes"
 aix="no"
 pie=""
+tcg="yes"
 
 # parse CC options first
 for opt do
@@ -191,6 +192,10 @@ for opt do
   --extra-ldflags=*) LDFLAGS="$optarg $LDFLAGS"
                      EXTRA_LDFLAGS="$optarg"
   ;;
+  --disable-tcg) tcg="no"
+  ;;
+  --enable-tcg) tcg="yes"
+  ;;
   --enable-debug-info) debug_info="yes"
   ;;
   --disable-debug-info) debug_info="no"
@@ -1150,7 +1155,6 @@ echo "python            $python"
 echo "host CPU          $cpu"
 echo "host big endian   $bigendian"
 echo "target list       $target_list"
-echo "tcg debug enabled $debug_tcg"
 echo "strip binaries    $strip_opt"
 echo "static build      $static"
 echo "mingw32 support   $mingw32"
@@ -1158,6 +1162,11 @@ if test -n "$sparc_cpu"; then
     echo "Target Sparc Arch $sparc_cpu"
 fi
 echo "PIE               $pie"
+echo "TCG support       $tcg"
+if test "$tcg" = "yes" ; then
+    echo "TCG debug enabled $debug_tcg"
+    echo "TCG interpreter   $tcg_interpreter"
+fi
 
 config_host_mak="config-host.mak"
 
@@ -1217,9 +1226,12 @@ fi
 if test "$bswap_h" = "yes" ; then
   echo "CONFIG_MACHINE_BSWAP_H=y" >> $config_host_mak
 fi
+if test "$tcg" = "yes"; then
+  echo "CONFIG_TCG=y" >> $config_host_mak
   if test "$tcg_interpreter" = "yes" ; then
     echo "CONFIG_TCG_INTERPRETER=y" >> $config_host_mak
   fi
+fi
 
 # XXX: suppress that
 if [ "$bsd" = "yes" ] ; then