bpo-29556: Remove unused #include <langinfo.h> (#98)

bltinmodule.c: Added in b744ba1 and no longer necessary since d64e8a7
posixmodule.c: Added in d1cd4d4 and no longer necessary since efb00c0
pythonrun.c:   Added in 73d538b and no longer necessary since d600951
sysmodule.c:   Added in 5467d4c and no longer necessary since a2c17c5
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index ffe4815..ae03d06 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -87,10 +87,6 @@
 #include <sys/loadavg.h>
 #endif
 
-#ifdef HAVE_LANGINFO_H
-#include <langinfo.h>
-#endif
-
 #ifdef HAVE_SYS_SENDFILE_H
 #include <sys/sendfile.h>
 #endif
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 763c2a2..63f1998 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -11,10 +11,6 @@
 
 #include <ctype.h>
 
-#ifdef HAVE_LANGINFO_H
-#include <langinfo.h>   /* CODESET */
-#endif
-
 /* The default encoding used by the platform file system APIs
    Can remain NULL for all platforms that don't have such a concept
 
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 5bddbad..b7016d1 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -25,10 +25,6 @@
 #include "malloc.h" /* for alloca */
 #endif
 
-#ifdef HAVE_LANGINFO_H
-#include <langinfo.h>
-#endif
-
 #ifdef MS_WINDOWS
 #undef BYTE
 #include "windows.h"
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 81520ea..c317b43 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -33,10 +33,6 @@
 extern const char *PyWin_DLLVersionString;
 #endif
 
-#ifdef HAVE_LANGINFO_H
-#include <langinfo.h>
-#endif
-
 _Py_IDENTIFIER(_);
 _Py_IDENTIFIER(__sizeof__);
 _Py_IDENTIFIER(buffer);