Canonicalize the path used by sh.

With a bunch of LibC work to support the feature. LibC now initializes
AK::StringImpl by default. It's now fine to use AK in LibC/Userland! :^)

LibC/stdlib.h

@@ -6,6 +6,11 @@ extern "C" {
 
 void* malloc(size_t);
 void free(void*);
+void* calloc(size_t nmemb, size_t);
+void* realloc(void *ptr, size_t);
+
+void exit(int status);
+void abort();
 
 }