implemented lt_db_set_datadir() override

+ added lt_db_set_datadir() and lb_db_get_datadir() functions to point to
  liblangtag data and override REGDATADIR define
- removed LIBO_LANGTAG_DATADIR environment variable hack

liblangtag/liblangtag-0.2-datadir.patch

+--- misc/liblangtag-0.2/liblangtag/lt-database.c	2012-01-31 11:27:16.000000000 +0100
++++ misc/build/liblangtag-0.2/liblangtag/lt-database.c	2012-06-12 01:32:57.354123185 +0200
+@@ -26,6 +26,7 @@
+ #include "lt-mem.h"
+ #include "lt-ext-module.h"
+ #include "lt-database.h"
++#include <string.h>
+ 
+ 
+ /**
+@@ -44,10 +45,41 @@
+ static lt_grandfathered_db_t *__db_grandfathered = NULL;
+ static lt_redundant_db_t     *__db_redundant = NULL;
+ 
++/* this is a hack and might need some proper runtime de/allocation, but ... */
++#define DATADIR_MAX_PATH_LEN 512
++static char lt_db_datadir[DATADIR_MAX_PATH_LEN] = { 0 };
++
+ 
+ /*< private >*/
+ 
+ /*< public >*/
++
++/**
++ * lt_db_set_datadir:
++ *
++ * Set the directory where database files are installed.
++ * This overrides the default prefix= location if called before 
++ * lt_db_initialize().
++ */
++void
++lt_db_set_datadir(const char* path)
++{
++    strncpy( lt_db_datadir, path, DATADIR_MAX_PATH_LEN-1);
++    lt_db_datadir[DATADIR_MAX_PATH_LEN-1] = 0;
++}
++
++/**
++ * lt_db_get_datadir:
++ *
++ * Obtain the directory where database files are installed.
++ * Only if set with lt_db_set_datadir().
++ */
++const char*
++lt_db_get_datadir(void)
++{
++    return lt_db_datadir;
++}
++
+ /**
+  * lt_db_initialize:
+  *
+--- misc/liblangtag-0.2/liblangtag/lt-database.h	2012-01-31 11:27:04.000000000 +0100
++++ misc/build/liblangtag-0.2/liblangtag/lt-database.h	2012-06-12 00:23:04.345618028 +0200
+@@ -37,6 +37,8 @@
+ 
+ G_BEGIN_DECLS
+ 
++void                   lt_db_set_datadir      (const char*);
++const char*            lt_db_get_datadir      (void);
+ void                   lt_db_initialize       (void);
+ void                   lt_db_finalize         (void);
+ lt_lang_db_t          *lt_db_get_lang         (void);
 --- misc/liblangtag-0.2/liblangtag/lt-xml.c	2012-02-02 09:54:51.000000000 +0100
-+++ misc/build/liblangtag-0.2/liblangtag/lt-xml.c	2012-06-04 17:39:32.010299830 +0200
-@@ -45,6 +45,14 @@
++++ misc/build/liblangtag-0.2/liblangtag/lt-xml.c	2012-06-12 00:23:04.477618565 +0200
+@@ -45,7 +45,20 @@
  
  G_LOCK_DEFINE_STATIC (lt_xml);
  
-+static const char* get_datadir()
++
++/* defined in lt-database.c */
++extern const char* lt_db_get_datadir(void);
++
+ /*< private >*/
++static const char*
++lt_xml_get_datadir()
 +{
-+    const char* pEnv = getenv( "LIBO_LANGTAG_DATADIR");
-+    if (pEnv && *pEnv)
-+        return pEnv;
++    const char* datadir = lt_db_get_datadir();
++    if (datadir && *datadir)
++        return datadir;
 +    return REGDATADIR;
 +}
 +
- /*< private >*/
  static gboolean
  lt_xml_read_subtag_registry(lt_xml_t  *xml,
-@@ -62,7 +70,7 @@
+ 			    GError   **error)
+@@ -62,7 +75,7 @@
  	if (!g_file_test(regfile, G_FILE_TEST_EXISTS)) {
  		g_free(regfile);
  #endif
 -	regfile = g_build_filename(REGDATADIR, "language-subtag-registry.xml", NULL);
-+	regfile = g_build_filename(get_datadir(), "language-subtag-registry.xml", NULL);
++	regfile = g_build_filename(lt_xml_get_datadir(), "language-subtag-registry.xml", NULL);
  #ifdef GNOME_ENABLE_DEBUG
  	}
  #endif
-@@ -120,7 +128,7 @@
+@@ -120,7 +133,7 @@
  	if (!g_file_test(regfile, G_FILE_TEST_EXISTS)) {
  		g_free(regfile);
  #endif
 -	regfile = g_build_filename(REGDATADIR, "common", "bcp47", filename, NULL);
-+	regfile = g_build_filename(get_datadir(), "common", "bcp47", filename, NULL);
++	regfile = g_build_filename(lt_xml_get_datadir(), "common", "bcp47", filename, NULL);
  #ifdef GNOME_ENABLE_DEBUG
  	}
  #endif