Kernel+LibC: Add a dbgputstr() syscall for sending strings to debug output.

This is very handy for the DebugLogStream implementation, among others. :^)

Kernel/kprintf.cpp

@@ -57,12 +57,18 @@ int ksprintf(char* buffer, const char* fmt, ...)
     return ret;
 }
 
+extern "C" int dbgputstr(const char* characters, int length)
+{
+    for (int i = 0; i < length; ++i)
+        IO::out8(0xe9, characters[i]);
+    return 0;
+}
+
 static void debugger_putch(char*&, char ch)
 {
     IO::out8(0xe9, ch);
 }
 
-
 extern "C" int dbgprintf(const char* fmt, ...)
 {
     color_on();