fix: add missing sys_includes to reduce cbindgen type warnings

- wchar.h: add stddef.h (wint_t/wchar_t), stdarg.h (va_list), stdio.h (FILE)
- ctype.h: add stddef.h (wint_t)
- string.h: add features.h, strings.h
- sys_wait.h: add stdint.h (siginfo_t types)
- sys_socket.h: add sys/un.h (sockaddr_un)

src/header/ctype/cbindgen.toml

@@ -4,7 +4,7 @@
 # - "The <ctype.h> header shall define the locale_t type as described in <locale.h>, representing a locale object."
 #
 # features.h included for #[deprecated] annotation
-sys_includes = ["features.h"]
+sys_includes = ["features.h", "stddef.h"]
 include_guard = "_RELIBC_CTYPE_H"
 after_includes = """
 #include <bits/locale-t.h> // for locale_t

src/header/string/cbindgen.toml

@@ -4,7 +4,7 @@
 # - "The <string.h> header shall define NULL and size_t as described in <stddef.h>."
 # - "The <string.h> header shall define the locale_t type as described in <locale.h>."
 # - "Inclusion of the <string.h> header may also make visible all symbols from <stddef.h>."
-sys_includes = ["stddef.h"]
+sys_includes = ["stddef.h", "features.h", "strings.h"]
 include_guard = "_RELIBC_STRING_H"
 after_includes = """
 #include <bits/locale-t.h> // for locale_t from locale.h

src/header/sys_socket/cbindgen.toml

@@ -1,4 +1,4 @@
-sys_includes = ["stddef.h", "stdint.h", "sys/types.h"]
+sys_includes = ["stddef.h", "stdint.h", "sys/types.h", "sys/un.h"]
 include_guard = "_RELIBC_SYS_SOCKET_H"
 after_includes = """
 #include <bits/iovec.h> // for iovec from sys/uio.h

src/header/sys_wait/cbindgen.toml

@@ -1,4 +1,4 @@
-sys_includes = ["sys/types.h", "sys/resource.h", "signal.h"]
+sys_includes = ["sys/types.h", "sys/resource.h", "signal.h", "stdint.h"]
 include_guard = "_RELIBC_SYS_WAIT_H"
 after_includes = """
 

src/header/wchar/cbindgen.toml

@@ -1,4 +1,4 @@
-sys_includes = ["features.h"]
+sys_includes = ["features.h", "stddef.h", "stdarg.h", "stdio.h"]
 after_includes = """
 // int32_t, uint32_t, WCHAR_MIN, WCHAR_MAX
 #include <stdint.h>