libical: fix crash when TZDIR is empty, and add non-nixos zoneinfo paths. Closes #8285

diff --git a/src/libical/icaltz-util.c b/src/libical/icaltz-util.c

index fe984c9..22ba0a1 100644

--- a/src/libical/icaltz-util.c

+++ b/src/libical/icaltz-util.c

@@ -107,7 +107,7 @@ typedef struct

--- a/src/libical/icaltz-util.c	2015-06-11 15:40:58.843138630 +0200

+++ b/src/libical/icaltz-util.c	2015-06-11 15:43:12.722046252 +0200

@@ -107,7 +107,7 @@

 	char	charcnt[4];			

 } tzinfo; 

-static char *search_paths [] = {"/usr/share/zoneinfo","/usr/lib/zoneinfo","/etc/zoneinfo","/usr/share/lib/zoneinfo"};

+static char *search_paths [] = {"/etc/zoneinfo"};

+static char *search_paths [] = {"/etc/zoneinfo","/usr/share/zoneinfo","/usr/lib/zoneinfo","/usr/share/lib/zoneinfo"};

 static char *zdir = NULL;

 #define NUM_SEARCH_PATHS (sizeof (search_paths)/ sizeof (search_paths [0]))

@@ -194,6 +194,16 @@ set_zonedir (void)

@@ -194,6 +194,15 @@

 	const char *fname = ZONES_TAB_SYSTEM_FILENAME;

 	unsigned int i;

+	const char *env_tzdir = strdup (getenv ("TZDIR"));

+	const char *env_tzdir = getenv ("TZDIR");

+	if (env_tzdir) {

+		sprintf (file_path, "%s/%s", env_tzdir, fname);

+		if (!access (file_path, F_OK|R_OK)) {

+			zdir = env_tzdir;

+			return;

+		}

+		free (env_tzdir);

+	}

+

 	for (i = 0; i < NUM_SEARCH_PATHS; i++) {