Some refactoring and cleanup (#1806)

* Use clang-tidy `misc-include-cleaner` for IWYU `#include` cleanup

* Use `std::optional<size_t>` instead of `ssize_t`

* Rename some functions in linkdefs.hpp

* Fix header order

include/asm/actions.hpp

@@ -4,14 +4,16 @@
 #define RGBDS_ASM_ACTIONS_HPP
 
 #include <optional>
+#include <stddef.h>
 #include <stdint.h>
 #include <string>
 #include <string_view>
 #include <variant>
 #include <vector>
 
-#include "asm/output.hpp" // AssertionType
-#include "asm/rpn.hpp"    // RPNCommand
+#include "linkdefs.hpp" // AssertionType, RPNCommand
+
+#include "asm/rpn.hpp" // Expression
 
 struct AlignmentSpec {
 	uint8_t alignment;

include/asm/charmap.hpp

@@ -4,6 +4,7 @@
 #define RGBDS_ASM_CHARMAP_HPP
 
 #include <optional>
+#include <stddef.h>
 #include <stdint.h>
 #include <string>
 #include <string_view>

include/asm/lexer.hpp

@@ -6,6 +6,7 @@
 #include <deque>
 #include <memory>
 #include <optional>
+#include <stddef.h>
 #include <stdint.h>
 #include <string>
 #include <variant>

include/asm/main.hpp

@@ -7,8 +7,6 @@
 #include <stdio.h>
 #include <string>
 
-#include "verbosity.hpp"
-
 enum MissingInclude {
 	INC_ERROR,    // A missing included file is an error that halts assembly
 	GEN_EXIT,     // A missing included file is assumed to be generated; exit normally

include/asm/output.hpp

@@ -6,7 +6,6 @@
 #include <memory>
 #include <stdint.h>
 #include <string>
-#include <unordered_map>
 #include <vector>
 
 #include "linkdefs.hpp"

include/asm/section.hpp

@@ -6,9 +6,9 @@
 #include <deque>
 #include <memory>
 #include <optional>
+#include <stddef.h>
 #include <stdint.h>
 #include <string>
-#include <unordered_map>
 #include <vector>
 
 #include "linkdefs.hpp"

include/asm/symbol.hpp

@@ -5,9 +5,7 @@
 
 #include <memory>
 #include <stdint.h>
-#include <string.h>
 #include <string>
-#include <string_view>
 #include <time.h>
 #include <utility>
 #include <variant>