Update comments for POSIX 2024 change.

Author: nascheme

Tools/configure/conf_extlibs.py

@@ -528,7 +528,7 @@ def check_readline(v):
             else:
                 with_readline = False
 
-    # Strip -D_XOPEN_SOURCE=600 from READLINE_CFLAGS (pyconfig.h defines _XOPEN_SOURCE=700)
+    # Strip -D_XOPEN_SOURCE=600 from READLINE_CFLAGS (pyconfig.h defines _XOPEN_SOURCE=800)
     v.export(
         "READLINE_CFLAGS",
         v.READLINE_CFLAGS.replace("-D_XOPEN_SOURCE=600", "").strip(),
@@ -934,7 +934,7 @@ def check_curses(v):
                 _have_any_curses_h = True
                 break
         if _have_any_curses_h:
-            # Strip -D_XOPEN_SOURCE=600 (pyconfig.h sets 700)
+            # Strip -D_XOPEN_SOURCE=600 (pyconfig.h sets 800)
             curses_cflags = curses_cflags.replace(
                 "-D_XOPEN_SOURCE=600", ""
             ).strip()

Tools/configure/conf_platform.py

@@ -264,11 +264,16 @@ def setup_xopen_source(v):
         v.define_xopen_source = False
 
     if v.define_xopen_source:
+        # X/Open 8, incorporating POSIX.1-2024
         pyconf.define(
             "_XOPEN_SOURCE",
             800,
             "Define to the level of X/Open that your system supports",
         )
+        # On Tru64 Unix 4.0F, defining _XOPEN_SOURCE also requires
+        # definition of _XOPEN_SOURCE_EXTENDED and _POSIX_C_SOURCE, or else
+        # several APIs are not declared. Since this is also needed in some
+        # cases for HP-UX, we define it globally.
         pyconf.define(
             "_XOPEN_SOURCE_EXTENDED",
             1,
@@ -281,6 +286,7 @@ def setup_xopen_source(v):
         )
 
     if v.ac_sys_system.startswith(("hp", "HP")):
+        # On HP-UX mbstate_t requires _INCLUDE__STDC_A1_SOURCE
         pyconf.define(
             "_INCLUDE__STDC_A1_SOURCE",
             1,