wchar: make the HP-UX workaround work on HP-UX 11.31

[Bruno Haible]

On HP-UX 11.31 I observe that the gnulib overrides in <wchar.h> are not
activated. This is caused by the #if at the beginning of the file, which
contains a prevention against trouble on HP-UX 11.00.

The difference between HP-UX 11.00 and 11.31 here is that in 11.00 the
system's <inttypes.h> defines 'strtoimax' as a macro, which we could use
to test whether <inttypes.h> has being completely included or not. This
trick does not work with 11.31 any more, because it no longer defines
such macros in <inttypes.h>.

This patch fixes it, by providing our own witness macro that tells whether
the system's <inttypes.h> has being completely included.


2020-01-02  Bruno Haible  <address@hidden>

        wchar: Make the HP-UX workaround work on HP-UX 11.31.
        * modules/wchar (Depends-on): Add inttypes-incomplete.
        * lib/inttypes.in.h: Define _GL_FINISHED_INCLUDING_SYSTEM_INTTYPES_H.
        * lib/wchar.in.h: Test _GL_FINISHED_INCLUDING_SYSTEM_INTTYPES_H instead
        of strtoimax.

diff --git a/lib/inttypes.in.h b/lib/inttypes.in.h
index 5184e26..d6efc7e 100644
--- a/lib/inttypes.in.h
+++ b/lib/inttypes.in.h
@@ -38,6 +38,8 @@
 #  endif
 
 #  @INCLUDE_NEXT@ @NEXT_INTTYPES_H@
+
+#  define _GL_FINISHED_INCLUDING_SYSTEM_INTTYPES_H
 # endif
 #endif
 
diff --git a/lib/wchar.in.h b/lib/wchar.in.h
index 3eaa7a6..834b3e8 100644
--- a/lib/wchar.in.h
+++ b/lib/wchar.in.h
@@ -33,7 +33,8 @@
 #if (((defined __need_mbstate_t || defined __need_wint_t)               \
       && !defined __MINGW32__)                                          \
      || (defined __hpux                                                 \
-         && ((defined _INTTYPES_INCLUDED && !defined strtoimax)         \
+         && ((defined _INTTYPES_INCLUDED                                \
+              && !defined _GL_FINISHED_INCLUDING_SYSTEM_INTTYPES_H)     \
              || defined _GL_JUST_INCLUDE_SYSTEM_WCHAR_H))               \
      || (defined __MINGW32__ && defined __STRING_H_SOURCED__)           \
      || defined _GL_ALREADY_INCLUDING_WCHAR_H)
diff --git a/modules/wchar b/modules/wchar
index a943740..cd4464b 100644
--- a/modules/wchar
+++ b/modules/wchar
@@ -12,6 +12,7 @@ include_next
 snippet/arg-nonnull
 snippet/c++defs
 snippet/warn-on-use
+inttypes-incomplete
 stddef
 
 configure.ac: