Add clang-format file

Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.

Kernel/kstdio.h

@@ -1,11 +1,11 @@
 #pragma once
 
 extern "C" {
-int dbgprintf(const char *fmt, ...);
-int kprintf(const char *fmt, ...);
-int ksprintf(char* buf, const char *fmt, ...);
+int dbgprintf(const char* fmt, ...);
+int kprintf(const char* fmt, ...);
+int ksprintf(char* buf, const char* fmt, ...);
 }
 
 #ifndef USERLAND
-#define printf dbgprintf
+#    define printf dbgprintf
 #endif