AK: Remove unused PrintfImplementation.h

Author: https://github.com/awesomekling
Commit: 6df5785fc4
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/197
Reviewed-by: https://github.com/ADKaster

AK/StringBuilder.cpp

@@ -9,7 +9,6 @@
 #include <AK/ByteString.h>
 #include <AK/Checked.h>
 #include <AK/FlyString.h>
-#include <AK/PrintfImplementation.h>
 #include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
@@ -122,14 +121,6 @@ void StringBuilder::append(char ch)
     MUST(try_append(ch));
 }
 
-void StringBuilder::appendvf(char const* fmt, va_list ap)
-{
-    printf_internal([this](char*&, char ch) {
-        append(ch);
-    },
-        nullptr, fmt, ap);
-}
-
 void StringBuilder::append_repeated(char ch, size_t n)
 {
     MUST(try_append_repeated(ch, n));