liblangtag: harmonize ENABLE_* variable to use TRUE/<nothing>

Change-Id: I6e231516476f3b9512e239ccf678048c87d25aa5
Reviewed-on: https://gerrit.libreoffice.org/5682Reviewed-by: Fridrich Strba <fridrich@documentfoundation.org>
Tested-by: Fridrich Strba <fridrich@documentfoundation.org>

RepositoryExternal.mk

@@ -825,7 +825,7 @@ define gb_LinkTarget__use_glib
 $(error gb_LinkTarget__use_glib should not be called any more)
 endef
 
-ifeq ($(ENABLE_LIBLANGTAG),YES)
+ifeq ($(ENABLE_LIBLANGTAG),TRUE)
 
 ifeq ($(SYSTEM_LIBLANGTAG),YES)
 

configure.ac

@@ -11621,7 +11621,7 @@ ENABLE_LIBLANGTAG=
 SYSTEM_LIBLANGTAG=
 AC_MSG_CHECKING([whether to use liblangtag])
 if test "$enable_liblangtag" = "yes" -o \( "$enable_liblangtag" = "" -a $_os != Android -a $_os != iOS \); then
-    ENABLE_LIBLANGTAG=YES
+    ENABLE_LIBLANGTAG=TRUE
     AC_MSG_RESULT([yes])
     AC_MSG_CHECKING([whether to use system liblangtag])
     if test "$with_system_liblangtag" = yes; then
@@ -11636,7 +11636,6 @@ if test "$enable_liblangtag" = "yes" -o \( "$enable_liblangtag" = "" -a $_os !=
         BUILD_TYPE="$BUILD_TYPE LIBLANGTAG"
     fi
 else
-    ENABLE_LIBLANGTAG=NO
     AC_MSG_RESULT([no])
 fi
 AC_SUBST(ENABLE_LIBLANGTAG)

i18nlangtag/CppunitTest_i18nlangtag_test_languagetag.mk

@@ -22,7 +22,7 @@ $(eval $(call gb_CppunitTest_use_libraries,i18nlangtag_test_languagetag,\
 	$(gb_UWINAPI) \
 ))
 
-ifeq ($(ENABLE_LIBLANGTAG),YES)
+ifeq ($(ENABLE_LIBLANGTAG),TRUE)
 $(eval $(call gb_CppunitTest_use_externals,i18nlangtag_test_languagetag,\
 	liblangtag \
 	libxml2 \

i18nlangtag/Library_i18nlangtag.mk

@@ -34,7 +34,7 @@ $(eval $(call gb_Library_add_exception_objects,i18nlangtag,\
 ))
 
 
-ifeq ($(ENABLE_LIBLANGTAG),YES)
+ifeq ($(ENABLE_LIBLANGTAG),TRUE)
 $(eval $(call gb_Library_add_defs,i18nlangtag,-DENABLE_LIBLANGTAG))
 $(eval $(call gb_Library_use_external,i18nlangtag,liblangtag))
 $(eval $(call gb_Library_use_external,i18nlangtag,libxml2))

liblangtag/Module_liblangtag.mk

@@ -9,7 +9,7 @@
 
 $(eval $(call gb_Module_Module,liblangtag))
 
-ifeq ($(ENABLE_LIBLANGTAG),YES)
+ifeq ($(ENABLE_LIBLANGTAG),TRUE)
 ifeq ($(SYSTEM_LIBLANGTAG),NO)
 
 $(eval $(call gb_Module_add_targets,liblangtag,\