[kernel] Use symbol table in stack traces

Now using the symbol table built by build_symbol_table.py in the kernel
when printing stack traces.

src/libraries/initrd/include/initrd/headers.h

@@ -21,7 +21,8 @@ struct disk_header
 
 enum class file_flags : uint16_t
 {
-	executable = 0x01
+	executable = 0x01,
+	symbols    = 0x02
 };
 
 struct file_header

src/libraries/initrd/include/initrd/initrd.h

@@ -36,6 +36,9 @@ public:
 	/// Whether this file is an executable
 	bool executable() const;
 
+	/// Whether this file is a symbol table
+	bool symbols() const;
+
 private:
 	const file_header *m_header;
 	void const *m_data;

src/libraries/initrd/initrd.cpp

@@ -22,6 +22,11 @@ file::executable() const {
 	return bitfield_has(m_header->flags, file_flags::executable);
 }
 
+bool
+file::symbols() const {
+	return bitfield_has(m_header->flags, file_flags::symbols);
+}
+
 
 disk::disk(const void *start)
 {