LibC: add function declarations to sys/stat.h

kernel/kernel/Font.cpp

@@ -40,7 +40,7 @@ namespace Kernel
 		int fd = TRY(Process::current().open(path, O_RDONLY));
 		BAN::ScopeGuard _([fd] { MUST(Process::current().close(fd)); });
 
-		stat st;
+		struct stat st;
 		TRY(Process::current().fstat(fd, &st));
 
 		BAN::Vector<uint8_t> file_data;

kernel/kernel/Shell.cpp

@@ -522,7 +522,7 @@ argument_done:
 			TRY(entry_prefix.push_back('/'));
 			for (const auto& entry : all_entries)
 			{
-				stat st;
+				struct stat st;
 
 				BAN::String entry_path;
 				TRY(entry_path.append(entry_prefix));
@@ -572,7 +572,7 @@ argument_done:
 				return {};
 			}
 			
-			stat st;
+			struct stat st;
 			TRY(Process::current().stat(arguments[1], &st));
 
 			Inode::Mode mode { st.st_mode };