Clean up a couple of logic errors resulting in github action failures.

configure.ac

@@ -469,6 +469,7 @@ AC_ARG_ENABLE([legacy-macros],
  [AS_HELP_STRING([--enable-legacy-macros],
  [enable legacy macros for backwards compatibility purposes. Use with caution.\
  This can lead to unexpected consequences/behavior.])])
+test "x$enable_legacy_macros" = xyes || enable_legacy_macros=no
 if test "x$enable_legacy_macros" = xyes; then
  AC_DEFINE([NETCDF_ENABLE_LEGACY_MACROS], 1, [If true, enable legacy macros in netcdf.h])
 fi
@@ -2169,7 +2170,7 @@ elif test "x$with_plugin_dir" = xyes ; then # --with-plugin-dir, no argument
  if test "x$ISMSVC" = xyes || test "x$ISMINGW" = xyes; then
  PLUGIN_PATH="${ALLUSERSPROFILE}\\hdfd5\\lib\\plugin"
  else
-  if test "x${prefix}" = x ; then
+ if test "x${prefix}" = xNONE ; then
  PLUGIN_PATH="/usr/local/hdf5/lib/plugin"
  else 
  PLUGIN_PATH="${prefix}/hdf5/lib/plugin"