persist logs: remove persist from available log directories in
partitions.

Too many problems have been reported for TWRP attempting to store
logs in the persist partition. Selinux denials have caused issues
booting Android, and filling up persist has caused IMEI issues.

This patchset will remove persist from the list of available log
directories by default in order to avoid these and other possible
issues.

Change-Id: I29889d69f76270a8fbb764a79be3523821d8579c
diff --git a/twrp-functions.cpp b/twrp-functions.cpp
index ba0d8a5..9f13fe2 100755
--- a/twrp-functions.cpp
+++ b/twrp-functions.cpp
@@ -770,7 +770,7 @@
 	PartitionManager.Mount_By_Path(src, false);
 	PartitionManager.Mount_By_Path(dst, false);
 	if (!Path_Exists(src)) {
-		LOGINFO("Unable to find source file %s\n", src.c_str());
+		LOGINFO("Path %s does not exist. Unable to copy %s\n", src.c_str(), dst.c_str());
 		return -1;
 	}
 	std::ifstream srcfile(src.c_str(), ios::binary);
@@ -1259,11 +1259,8 @@
 std::string TWFunc::get_log_dir() {
 	if (PartitionManager.Find_Partition_By_Path(CACHE_LOGS_DIR) == NULL) {
 		if (PartitionManager.Find_Partition_By_Path(DATA_LOGS_DIR) == NULL) {
-			if (PartitionManager.Find_Partition_By_Path(PERSIST_LOGS_DIR) == NULL) {
-				LOGINFO("Unable to find a directory to store TWRP logs.");
-				return "";
-			}
-			return PERSIST_LOGS_DIR;
+			LOGINFO("Unable to find a directory to store TWRP logs.");
+			return "";
 		} else {
 			return DATA_LOGS_DIR;
 		}