base: avoid use of deprecated base/printf.h

Besides adapting the components to the use of base/log.h, the patch
cleans up a few base headers, i.e., it removes unused includes from
root/component.h, specifically base/heap.h and
ram_session/ram_session.h. Hence, components that relied on the implicit
inclusion of those headers have to manually include those headers now.

While adjusting the log messages, I repeatedly stumbled over the problem
that printing char * arguments is ambiguous. It is unclear whether to
print the argument as pointer or null-terminated string. To overcome
this problem, the patch introduces a new type 'Cstring' that allows the
caller to express that the argument should be handled as null-terminated
string. As a nice side effect, with this type in place, the optional len
argument of the 'String' class could be removed. Instead of supplying a
pair of (char const *, size_t), the constructor accepts a 'Cstring'.
This, in turn, clears the way let the 'String' constructor use the new
output mechanism to assemble a string from multiple arguments (and
thereby getting rid of snprintf within Genode in the near future).

To enforce the explicit resolution of the char * ambiguity, the 'char *'
overload of the 'print' function is marked as deleted.

Issue #1987

repos/base/include/util/volatile_object.h

@@ -15,7 +15,6 @@
 #define _INCLUDE__UTIL__VOLATILE_OBJECT_H_
 
 #include <util/construct_at.h>
-#include <base/printf.h>
 #include <base/stdint.h>
 
 namespace Genode {
@@ -61,11 +60,8 @@ class Genode::Volatile_object
 
 		void _check_constructed() const
 		{
-			if (!_constructed) {
-				PDBG("Deref_unconstructed_object");
-				PDBG("bt: %p", __builtin_return_address(0));
+			if (!_constructed)
 				throw Deref_unconstructed_object();
-			}
 		}
 
 	protected: