fs/Path: rename to AllocatedPath

The new class Path only holds a string pointer without being
responsible for allocation/deallocation.  The FileSystem.hxx library
accepts Path arguments instead of AllocatedPath, to avoid forcing
callers to allocate another string object.

src/db/SimpleDatabasePlugin.cxx

@@ -76,7 +76,7 @@ SimpleDatabase::Check(Error &error) const
 		/* If the file doesn't exist, we can't check if we can write
 		 * it, so we are going to try to get the directory path, and
 		 * see if we can write a file in that */
-		const Path dirPath = path.GetDirectoryName();
+		const auto dirPath = path.GetDirectoryName();
 
 		/* Check that the parent part of the path is a directory */
 		struct stat st;

src/db/SimpleDatabasePlugin.hxx

@@ -21,7 +21,7 @@
 #define MPD_SIMPLE_DATABASE_PLUGIN_HXX
 
 #include "DatabasePlugin.hxx"
-#include "fs/Path.hxx"
+#include "fs/AllocatedPath.hxx"
 #include "Compiler.h"
 
 #include <cassert>
@@ -31,7 +31,7 @@
 struct Directory;
 
 class SimpleDatabase : public Database {
-	Path path;
+	AllocatedPath path;
 	std::string path_utf8;
 
 	Directory *root;
@@ -43,7 +43,7 @@ class SimpleDatabase : public Database {
 #endif
 
 	SimpleDatabase()
-		:path(Path::Null()) {}
+		:path(AllocatedPath::Null()) {}
 
 public:
 	gcc_pure