meson: move libmpathpersist test

This is the first compiler/linker test that has been moved to Meson.
Add more section headings to keep things clearer.

This also fixes static linking to libmpathpersist, which has a
dependency on libmultipath but no pkg-config file to describe it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -403,7 +403,7 @@ netmap="no"
 sdl="auto"
 sdl_image="auto"
 virtfs=""
-mpath=""
+mpath="auto"
 vnc="enabled"
 sparse="no"
 vde=""
@@ -1116,9 +1116,9 @@ for opt do
   ;;
   --enable-virtfs) virtfs="yes"
   ;;
-  --disable-mpath) mpath="no"
+  --disable-mpath) mpath="disabled"
   ;;
-  --enable-mpath) mpath="yes"
+  --enable-mpath) mpath="enabled"
   ;;
   --disable-vnc) vnc="disabled"
   ;;
@@ -3852,57 +3852,6 @@ if test "$modules" = yes; then
     fi
 fi
 
-##########################################
-# libmpathpersist probe
-
-if test "$mpath" != "no" ; then
-  # probe for the new API
-  cat > $TMPC <<EOF
-#include <libudev.h>
-#include <mpath_persist.h>
-unsigned mpath_mx_alloc_len = 1024;
-int logsink;
-static struct config *multipath_conf;
-extern struct udev *udev;
-extern struct config *get_multipath_config(void);
-extern void put_multipath_config(struct config *conf);
-struct udev *udev;
-struct config *get_multipath_config(void) { return multipath_conf; }
-void put_multipath_config(struct config *conf) { }
-
-int main(void) {
-    udev = udev_new();
-    multipath_conf = mpath_lib_init();
-    return 0;
-}
-EOF
-  if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
-    mpathpersist=yes
-    mpathpersist_new_api=yes
-  else
-    # probe for the old API
-    cat > $TMPC <<EOF
-#include <libudev.h>
-#include <mpath_persist.h>
-unsigned mpath_mx_alloc_len = 1024;
-int logsink;
-int main(void) {
-    struct udev *udev = udev_new();
-    mpath_lib_init(udev);
-    return 0;
-}
-EOF
-    if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
-      mpathpersist=yes
-      mpathpersist_new_api=no
-    else
-      mpathpersist=no
-    fi
-  fi
-else
-  mpathpersist=no
-fi
-
 ##########################################
 # pthread probe
 PTHREADLIBS_LIST="-pthread -lpthread -lpthreadGC2"
@@ -6337,23 +6286,11 @@ if test "$softmmu" = yes ; then
       fi
       virtfs=no
     fi
-    if test "$mpath" != no && test "$mpathpersist" = yes ; then
-      mpath=yes
-    else
-      if test "$mpath" = yes; then
-        error_exit "Multipath requires libmpathpersist devel"
-      fi
-      mpath=no
-    fi
   else
     if test "$virtfs" = yes; then
       error_exit "VirtFS is supported only on Linux"
     fi
     virtfs=no
-    if test "$mpath" = yes; then
-      error_exit "Multipath is supported only on Linux"
-    fi
-    mpath=no
   fi
 fi
 
@@ -6894,12 +6831,6 @@ fi
 if test "$virtfs" = "yes" ; then
   echo "CONFIG_VIRTFS=y" >> $config_host_mak
 fi
-if test "$mpath" = "yes" ; then
-  echo "CONFIG_MPATH=y" >> $config_host_mak
-  if test "$mpathpersist_new_api" = "yes"; then
-    echo "CONFIG_MPATH_NEW_API=y" >> $config_host_mak
-  fi
-fi
 if test "$vhost_scsi" = "yes" ; then
   echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak
 fi
@@ -7988,7 +7919,7 @@ NINJA=${ninja:-$PWD/ninjatool} $meson setup \
         -Dstrip=$(if test "$strip_opt" = yes; then echo true; else echo false; fi) \
         -Db_pie=$(if test "$pie" = yes; then echo true; else echo false; fi) \
         -Db_coverage=$(if test "$gcov" = yes; then echo true; else echo false; fi) \
-	-Dsdl=$sdl -Dsdl_image=$sdl_image \
+	-Dmpath=$mpath -Dsdl=$sdl -Dsdl_image=$sdl_image \
 	-Dvnc=$vnc -Dvnc_sasl=$vnc_sasl -Dvnc_jpeg=$vnc_jpeg -Dvnc_png=$vnc_png \
 	-Dgettext=$gettext -Dxkbcommon=$xkbcommon -Du2f=$u2f\
         $cross_arg \