[patch] libstdc++/66030 fix codecvt exports for mingw32

[Jonathan Wakely]

The linker script assumes that std::mbstate_t has the name __mbstate_t
for linkage purposes, but that's not necessarily true. For mingw32
it's just a typedef for int, so the patterns don't match.

This adds a new mingw32-specific pattern for codecvt_byname's
constructors and destructors, and relaxes the patterns for
codecvt<charNN_t, char, mbstate_t> so they match __mbstate_t or int.

Tested x86_64-linux and powerpc64le-linux, committed to trunk.

I plan to commit this to trunk and gcc-5-branch soon.

commit dffce5e2b48ff19c4ec4de5d7ca934c15225b940
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Jun 1 17:31:46 2015 +0100

    	PR libstdc++/66030
    	* config/abi/pre/gnu.ver: Export codecvt_byname and codecvt symbols
    	for mingw32.

diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 2da04e4..d42cd37 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -542,6 +542,9 @@ GLIBCXX_3.4 {
     # std::codecvt_byname
     _ZNSt14codecvt_bynameI[cw]c11__mbstate_tEC[12]EPKc[jmy];
     _ZNSt14codecvt_bynameI[cw]c11__mbstate_tED*;
+#if defined (_WIN32) && !defined (__CYGWIN__)
+    _ZNSt14codecvt_bynameI[cw]ciE[CD]*;
+#endif
 
     # std::collate
     _ZNSt7collateI[cw]*;
@@ -1821,9 +1824,9 @@ GLIBCXX_3.4.21 {
     _ZNKSt8time_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE6do_getES3_S3_RSt8ios_baseRSt12_Ios_IostateP2tmcc;
 
     # codecvt<char16_t, char, mbstate_t>, codecvt<char32_t, char, mbstate_t>
-    _ZNKSt7codecvtID[is]c11__mbstate_t*;
-    _ZNSt7codecvtID[is]c11__mbstate_t*;
-    _ZT[ISV]St7codecvtID[is]c11__mbstate_tE;
+    _ZNKSt7codecvtID[is]c*;
+    _ZNSt7codecvtID[is]c*;
+    _ZT[ISV]St7codecvtID[is]c*E;
 
     extern "C++"
     {