Add get_*architecture() API, extend find_path*() API

* Add get_architecture(), get_primary_architecture(),
  get_secondary_architectures(), guess_architecture_for_path() to get
  the caller's architecture, the primary architecture, all secondary
  architectures, or the architecture associated with a specified path
  respectively.
* Rename the find_path*() functions to find_path*_etc() and add an
  optional architecture parameter. Add simplified find_path*()
  functions.
* BPathFinder: Add FindPath[s]() versions with an architecture
  parameter.

headers/os/support/Architecture.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2013, Haiku, Inc. All Rights Reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _SUPPORT_ARCHITECTURE_H
+#define _SUPPORT_ARCHITECTURE_H
+
+
+#include <sys/cdefs.h>
+
+#include <sys/types.h>
+
+
+__BEGIN_DECLS
+
+
+const char*	get_architecture();
+const char*	get_primary_architecture();
+size_t		get_secondary_architectures(const char** architectures,
+				size_t count);
+const char*	guess_architecture_for_path(const char* path);
+
+
+__END_DECLS
+
+
+#endif	/* _SUPPORT_ARCHITECTURE_H */