Regressed by https://github.com/unicode-org/icu/commit/c3fe7e09d844

src/libical/icalrecur.c:1021:59: error: use of undeclared identifier 'FALSE'
    en = ucal_getKeywordValuesForLocale("calendar", NULL, FALSE, &status);
                                                          ^
src/libical/icalrecur.c:1414:63: error: use of undeclared identifier 'FALSE'
        en = ucal_getKeywordValuesForLocale("calendar", NULL, FALSE, &status);
                                                              ^

--- src/libical/icalrecur.c.orig	2020-03-07 14:42:42 UTC
+++ src/libical/icalrecur.c
@@ -1018,7 +1018,7 @@ icalarray *icalrecurrencetype_rscale_supported_calenda
 
     calendars = icalarray_new(sizeof(const char **), 20);
 
-    en = ucal_getKeywordValuesForLocale("calendar", NULL, FALSE, &status);
+    en = ucal_getKeywordValuesForLocale("calendar", NULL, false, &status);
     while ((cal = uenum_next(en, NULL, &status))) {
         cal = icalmemory_tmp_copy(cal);
         icalarray_append(calendars, &cal);
@@ -1411,7 +1411,7 @@ static int initialize_rscale(icalrecur_iterator *impl)
         }
 
         /* Check if specified calendar is supported */
-        en = ucal_getKeywordValuesForLocale("calendar", NULL, FALSE, &status);
+        en = ucal_getKeywordValuesForLocale("calendar", NULL, false, &status);
         while ((cal = uenum_next(en, NULL, &status))) {
             if (!strcmp(cal, rule.rscale)) {
                 is_hebrew = !strcmp(rule.rscale, "hebrew");