Only disable use of non-ANSI functions in strict ANSI mode under Windows.

The changes of r62518 fixed compilation of wx headers in g++ strict ANSI mode
(enabled by th use of -ansi or -std=c++{98,0x} options) with mingw32 but
broke it when using g++ in ANSI mode under Unix. The problems arose at least
due to redeclaration of isascii() with different exception specifier and due
to the lack of wxCRT_StrdupA() definition in the library.

Fix this by simply not disabling the use of non-ANSI functions such as
isascii() and strdup() under Unix as they are still available in the headers
by default because of _GNU_SOURCE predefined by g++.

Notice that if _GNU_SOURCE is explicitly undefined, compilation would probably
still be broken. To fix this we might check whether __USE_SVID is defined
under Linux. Unfortunately doing tests in configure is not an answer as
wxWidgets might not be compiled with the same -std option as the programs
using it, so there is no obviously correct way to fix this.

See #11374.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63164 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/filefn.h

@@ -357,7 +357,7 @@ enum wxFileKind
 
     // finally the default char-type versions
     #if wxUSE_UNICODE
-        #if wxUSE_UNICODE_MSLU || defined(__STRICT_ANSI__)
+        #if wxUSE_UNICODE_MSLU || defined(__WX_STRICT_ANSI_GCC__)
             // implement the missing file functions in Win9x ourselves
             WXDLLIMPEXP_BASE int wxMSLU__wopen(const wxChar *name,
                                                int flags, int mode);

include/wx/wxcrtbase.h

@@ -52,12 +52,24 @@
     char *strtok_r(char *, const char *, char **);
 #endif
 
+/*
+    Using -std=c++{98,0x} option with mingw32 disables most of standard
+    library extensions, so we can't rely on the presence of common non-ANSI
+    functions, define a special symbol to test for this. Notice that this
+    doesn't need to be done for g++ under Linux where _GNU_SOURCE (which is
+    defined by default) still makes all common extensions available even in
+    ANSI mode.
+ */
+#if defined(__MINGW32__) && defined(__STRICT_ANSI__)
+    #define __WX_STRICT_ANSI_GCC__
+#endif
+
 /*
    a few compilers don't have the (non standard but common) isascii function,
    define it ourselves for them
  */
 #ifndef isascii
-    #if defined(__MWERKS__) || defined(__STRICT_ANSI__)
+    #if defined(__MWERKS__) || defined(__WX_STRICT_ANSI_GCC__)
         #define wxNEED_ISASCII
     #elif defined(_WIN32_WCE)
         #if _WIN32_WCE <= 211
@@ -180,12 +192,15 @@ WXDLLIMPEXP_BASE void *calloc( size_t num, size_t size );
    Mac and OpenVMS do not have wcsdup: */
 #if defined(__VISUALC__) && __VISUALC__ >= 1400
     #define wxCRT_StrdupA _strdup
-#elif !(defined(__MWERKS__) && defined(__WXMAC__)) && !defined(__WXWINCE__) && !defined(__STRICT_ANSI__)
+#elif !((defined(__MWERKS__) && defined(__WXMAC__)) || \
+        defined(__WXWINCE__) || \
+        defined(__WX_STRICT_ANSI_GCC__))
     #define wxCRT_StrdupA strdup
 #endif
 
-// all compilers except Cygwin provide _wcsdup() under Windows
+// most Windows compilers provide _wcsdup()
-#if defined(__WINDOWS__) && !defined(__CYGWIN__) && !defined(__STRICT_ANSI__)
+#if defined(__WINDOWS__) && \
+        !(defined(__CYGWIN__) || defined(__WX_STRICT_ANSI_GCC__))
     #define wxCRT_StrdupW _wcsdup
 #elif defined(HAVE_WCSDUP)
     #define wxCRT_StrdupW wcsdup
@@ -266,7 +281,7 @@ WXDLLIMPEXP_BASE void *calloc( size_t num, size_t size );
         (defined(__MWERKS__) && defined(__INTEL__))
     #define wxCRT_StricmpA _stricmp
     #define wxCRT_StrnicmpA _strnicmp
-#elif defined(__UNIX__) || (defined(__GNUWIN32__) && !defined(__STRICT_ANSI__))
+#elif defined(__UNIX__) || (defined(__GNUWIN32__) && !defined(__WX_STRICT_ANSI_GCC__))
     #define wxCRT_StricmpA strcasecmp
     #define wxCRT_StrnicmpA strncasecmp
 /* #else -- use wxWidgets implementation */
@@ -460,7 +475,7 @@ WXDLLIMPEXP_BASE wchar_t *wxCRT_StrtokW(wchar_t *psz, const wchar_t *delim, wcha
 #else /* Unicode filenames */
     /* special case: these functions are missing under Win9x with Unicows so we
        have to implement them ourselves */
-    #if wxUSE_UNICODE_MSLU || defined(__STRICT_ANSI__)
+    #if wxUSE_UNICODE_MSLU || defined(__WX_STRICT_ANSI_GCC__)
             WXDLLIMPEXP_BASE FILE* wxMSLU__wfopen(const wchar_t *name, const wchar_t *mode);
             WXDLLIMPEXP_BASE FILE* wxMSLU__wfreopen(const wchar_t *name, const wchar_t *mode, FILE *stream);
             WXDLLIMPEXP_BASE int wxMSLU__wrename(const wchar_t *oldname, const wchar_t *newname);
@@ -575,7 +590,7 @@ WXDLLIMPEXP_BASE wchar_t * wxCRT_GetenvW(const wchar_t *name);
         #define wxCRT_AtolW         watol
     /* else: use ANSI versions */
     #endif
-#elif defined(wxHAVE_TCHAR_SUPPORT) && !defined(__STRICT_ANSI__)
+#elif defined(wxHAVE_TCHAR_SUPPORT) && !defined(__WX_STRICT_ANSI_GCC__)
     #define  wxCRT_AtoiW           _wtoi
     #define  wxCRT_AtolW           _wtol
     /* _wtof doesn't exist */