Bug 1261263 - Remove test for libstdc++ headers conflict with clang 3.3. r=froydnj

Also remove the hack around it.

build/autoconf/toolchain.m4

@@ -191,7 +191,6 @@ PATH=$_SAVE_PATH
 
 AC_DEFUN([MOZ_CXX11],
 [
-dnl Check whether gcc's c++0x mode works
 dnl Updates to the test below should be duplicated further below for the
 dnl cross-compiling case.
 AC_LANG_CPLUSPLUS
@@ -199,28 +198,6 @@ if test "$GNU_CXX"; then
     CXXFLAGS="$CXXFLAGS -std=gnu++0x"
     _ADDED_CXXFLAGS="-std=gnu++0x"
 
-    AC_CACHE_CHECK(for gcc c++0x headers bug without rtti,
-        ac_cv_cxx0x_headers_bug,
-        [AC_TRY_COMPILE([#include <memory>], [],
-                        ac_cv_cxx0x_headers_bug="no",
-                        ac_cv_cxx0x_headers_bug="yes")])
-
-    if test "$CLANG_CXX" -a "$ac_cv_cxx0x_headers_bug" = "yes"; then
-        CXXFLAGS="$CXXFLAGS -I$_topsrcdir/build/unix/headers"
-        _ADDED_CXXFLAGS="$_ADDED_CXXFLAGS -I$_topsrcdir/build/unix/headers"
-        AC_CACHE_CHECK(whether workaround for gcc c++0x headers conflict with clang works,
-            ac_cv_cxx0x_clang_workaround,
-            [AC_TRY_COMPILE([#include <memory>], [],
-                            ac_cv_cxx0x_clang_workaround="yes",
-                            ac_cv_cxx0x_clang_workaround="no")])
-
-        if test "ac_cv_cxx0x_clang_workaround" = "no"; then
-            AC_MSG_ERROR([Your toolchain does not support C++0x/C++11 mode properly. Please upgrade your toolchain])
-        fi
-    elif test "$ac_cv_cxx0x_headers_bug" = "yes"; then
-        AC_MSG_ERROR([Your toolchain does not support C++0x/C++11 mode properly. Please upgrade your toolchain])
-    fi
-
     if test -n "$CLANG_CC"; then
         dnl We'd normally just check for the version from CC_VERSION (fed
         dnl from __clang_major__ and __clang_minor__), but the clang that
@@ -310,27 +287,6 @@ EOF
         CXXFLAGS="$HOST_CXXFLAGS"
         CPPFLAGS="$HOST_CPPFLAGS"
         CXX="$HOST_CXX"
-        AC_CACHE_CHECK(for host gcc c++0x headers bug without rtti,
-            ac_cv_host_cxx0x_headers_bug,
-            [AC_TRY_COMPILE([#include <memory>], [],
-                            ac_cv_host_cxx0x_headers_bug="no",
-                            ac_cv_host_cxx0x_headers_bug="yes")])
-
-        if test "$host_compiler" = CLANG -a "$ac_cv_host_cxx0x_headers_bug" = "yes"; then
-            CXXFLAGS="$CXXFLAGS -I$_topsrcdir/build/unix/headers"
-            AC_CACHE_CHECK(whether workaround for host gcc c++0x headers conflict with host clang works,
-                ac_cv_host_cxx0x_clang_workaround,
-                [AC_TRY_COMPILE([#include <memory>], [],
-                                ac_cv_host_cxx0x_clang_workaround="yes",
-                                ac_cv_host_cxx0x_clang_workaround="no")])
-
-            if test "ac_cv_host_cxx0x_clang_workaround" = "no"; then
-                AC_MSG_ERROR([Your host toolchain does not support C++0x/C++11 mode properly. Please upgrade your toolchain])
-            fi
-            HOST_CXXFLAGS="$CXXFLAGS"
-        elif test "$ac_cv_host_cxx0x_headers_bug" = "yes"; then
-            AC_MSG_ERROR([Your host toolchain does not support C++0x/C++11 mode properly. Please upgrade your toolchain])
-        fi
         if test "$host_compiler" = CLANG; then
             AC_TRY_COMPILE([], [#if !__cpp_static_assert
                                 #error ISO WG21 SG10 feature test macros unsupported

build/unix/headers/bits/c++config.h

@@ -1,2 +0,0 @@
-#include_next <bits/c++config.h>
-#undef _GLIBCXX_USE_FLOAT128