Demangling hangs under cygwin, so disable it under

Estimated hours taken: 0.25
Branches: main, release

Demangling hangs under cygwin, so disable it under
cygwin.

configure.in:
scripts/parse_ml_options.sh-subr.in:
	Disable demangling under cygwin.

configure.in

@@ -3587,11 +3587,22 @@ PARSE_GRADE_OPTIONS=$top/scripts/parse_grade_options.sh-subr
 FINAL_GRADE_OPTIONS=$top/scripts/final_grade_options.sh-subr
 PARSE_ML_OPTIONS=$top/scripts/parse_ml_options.sh-subr
 CANONICAL_GRADE=$top/scripts/canonical_grade.sh-subr
+
+
+# demangling hangs on cygwin, so don't enable it.
+case "$host" in
+	*-cygwin*)
+		DEMANGLE=false ;;
+	*)
+		DEMANGLE=true ;;
+esac
+
 AC_SUBST_FILE(INIT_GRADE_OPTIONS)
 AC_SUBST_FILE(PARSE_GRADE_OPTIONS)
 AC_SUBST_FILE(FINAL_GRADE_OPTIONS)
 AC_SUBST_FILE(PARSE_ML_OPTIONS)
 AC_SUBST_FILE(CANONICAL_GRADE)
+AC_SUBST(DEMANGLE)
 
 # mercury_config includes configure.help to include the help for configure
 # in its `--help' output and man page.

scripts/parse_ml_options.sh-subr.in

@@ -41,7 +41,7 @@ case $FULLARCH in
 esac
 mercury_libs=default
 all_libs=default
-demangle=true
+demangle=@DEMANGLE@
 make_shared_lib=false
 leave_shlib_dirs_relative=false
 user_shlib_dirs=""