configure.ac - check for the present of icu 52.1 or higher

configure.ac

@@ -462,12 +462,13 @@ fi
 AM_CONDITIONAL([ENABLE_TRAINING], true)
 
 # Check location of icu headers
-PKG_CHECK_MODULES([ICU_UC], [icu-uc], [have_icu_uc=true], [have_icu_uc=false])
-PKG_CHECK_MODULES([ICU_I18N], [icu-i18n], [have_icu_i18n=true], [have_icu_i18n=false])
+PKG_CHECK_MODULES([ICU_UC], [icu-uc >= 52.1], [have_icu_uc=true], [have_icu_uc=false])
+PKG_CHECK_MODULES([ICU_I18N], [icu-i18n >= 52.1], [have_icu_i18n=true], [have_icu_i18n=false])
 if !($have_icu_uc && $have_icu_i18n); then
   AC_CHECK_HEADERS([unicode/uchar.h], [have_icu=true], [have_icu=false])
   if !($have_icu); then
-        AC_MSG_WARN([Training tools WILL NOT be built because of missing icu library.])
+        AC_MSG_WARN([icu 52.1 or higher is required, but was not found.])
+        AC_MSG_WARN([Training tools WILL NOT be built.])
         AC_MSG_WARN([Try to install libicu-devel package.])
         AM_CONDITIONAL([ENABLE_TRAINING], false)
   else