Clean up base-library structure

This patch moves the base library from src/base to src/lib/base,
flattens the library-internal directory structure, and moves the common
parts of the library-description files to base/lib/mk/base.inc and
base/lib/mk/base-common.inc.

Furthermore, the patch fixes a few cosmetic issues (whitespace and
comments only) that I encountered while browsing the result.

Fixes #1952

repos/base-linux/src/lib/base/debug.cc

@@ -0,0 +1,57 @@
+/*
+ * \brief  Linux-specific debug utilities
+ * \author Norman Feske
+ * \date   2009-05-16
+ */
+
+/*
+ * Copyright (C) 2009-2013 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/*
+ * With the enabled 'DEBUG' flag, status information can be printed directly
+ * via a Linux system call by using the 'raw_write_str' function. This output
+ * bypasses the Genode 'LOG' mechanism, which is useful for debugging low-level
+ * code such as a libC back-end.
+ */
+#define DEBUG 1
+
+
+#if DEBUG
+#include <linux_syscalls.h>
+#endif /* DEBUG */
+
+
+/**
+ * Write function targeting directly the Linux system call layer and bypassing
+ * any Genode code.
+ */
+extern "C" int raw_write_str(const char *str)
+{
+#if DEBUG
+	unsigned len = 0;
+	for (; str[len] != 0; len++);
+	lx_syscall(SYS_write, (int)1, str, len);
+	return len;
+#endif /* DEBUG */
+}
+
+
+/**
+ * Debug function waiting until the user presses return
+ *
+ * This function is there to delay the execution of a back-end function such
+ * that we have time to attack the GNU debugger to the running process. Once
+ * attached, we can continue execution and use 'gdb' for debugging. In the
+ * normal mode of operation, this function is never used.
+ */
+extern "C" void wait_for_continue(void)
+{
+#if DEBUG
+	char buf[16];
+	lx_syscall(SYS_read, (int)0, buf, sizeof(buf));
+#endif /* DEBUG */
+}