[libc] Add NULL macro definitions to header files

By the C standard, <locale.h>, <stddef.h> <stdio.h>, <stdlib.h>,
<string.h>, <time.h>, and <wchar.h> require NULL to be defined.

Author: saturn691

libc/include/CMakeLists.txt

@@ -255,6 +255,7 @@ add_header_macro(
   time.h
   DEPENDS
     .llvm_libc_common_h
+    .llvm-libc-macros.null_macro
     .llvm-libc-macros.time_macros
     .llvm-libc-types.clock_t
     .llvm-libc-types.time_t
@@ -329,6 +330,7 @@ add_header_macro(
   stdio.h
   DEPENDS
     .llvm-libc-macros.file_seek_macros
+    .llvm-libc-macros.null_macro
     .llvm-libc-macros.stdio_macros
     .llvm-libc-types.FILE
     .llvm-libc-types.cookie_io_functions_t
@@ -343,6 +345,7 @@ add_header_macro(
   ../libc/include/stdlib.yaml
   stdlib.h
   DEPENDS
+    .llvm-libc-macros.null_macro
     .llvm-libc-macros.stdlib_macros
     .llvm-libc-types.__atexithandler_t
     .llvm-libc-types.__qsortcompare_t
@@ -709,6 +712,7 @@ add_header_macro(
   wchar.h
   DEPENDS
     .llvm_libc_common_h
+    .llvm-libc-macros.null_macro
     .llvm-libc-macros.wchar_macros
     .llvm-libc-types.mbstate_t
     .llvm-libc-types.size_t
@@ -723,6 +727,7 @@ add_header_macro(
   DEPENDS
     .llvm_libc_common_h
     .llvm-libc-macros.locale_macros
+    .llvm-libc-macros.null_macro
     .llvm-libc-types.locale_t
     .llvm-libc-types.struct_lconv
 )

libc/include/locale.h.def

@@ -10,8 +10,8 @@
 #define LLVM_LIBC_LOCALE_H
 
 #include "__llvm-libc-common.h"
-
 #include "llvm-libc-macros/locale-macros.h"
+#include "llvm-libc-macros/null-macro.h"
 
 %%public_api()
 

libc/include/stdio.h.def

@@ -11,6 +11,7 @@
 
 #include "__llvm-libc-common.h"
 #include "llvm-libc-macros/file-seek-macros.h"
+#include "llvm-libc-macros/null-macro.h"
 #include "llvm-libc-macros/stdio-macros.h"
 
 #include <stdarg.h>

libc/include/stdlib.h.def

@@ -10,6 +10,7 @@
 #define LLVM_LIBC_STDLIB_H
 
 #include "__llvm-libc-common.h"
+#include "llvm-libc-macros/null-macro.h"
 #include "llvm-libc-macros/stdlib-macros.h"
 
 %%public_api()

libc/include/time.h.def

@@ -10,6 +10,7 @@
 #define LLVM_LIBC_TIME_H
 
 #include "__llvm-libc-common.h"
+#include "llvm-libc-macros/null-macro.h"
 #include "llvm-libc-macros/time-macros.h"
 
 %%public_api()

libc/include/wchar.h.def

@@ -10,6 +10,7 @@
 #define LLVM_LIBC_WCHAR_H
 
 #include "__llvm-libc-common.h"
+#include "llvm-libc-macros/null-macro.h"
 #include "llvm-libc-macros/wchar-macros.h"
 
 %%public_api()