This patch is needed to build gcc-5.5.0 on the Hurd.

Backported from upstream: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=6cd9cb89ebdc1e1394b81c4a418c2b3b0eb86c57

commit b590b96ebc3f5b42a4829170e069722dd940e2543
Author: jason <jason@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Sat May 9 04:50:23 2015 +0000

            * src/c++98/Makefile.am (AM_CXXFLAGS): Add -std=gnu++98.
            * src/c++98/Makefile.in: Regenerate.
            * src/Makefile.am (AM_CXXFLAGS): Add -std=gnu++98.
            * src/Makefile.in: Regenerate.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@222964 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index a5f48b22c6d..cd07ccd81bc 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -168,6 +168,7 @@ compatibility-condvar.o: compatibility-condvar.cc
 # OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
 # as the occasi</td></tr></table>
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<div class='content'><div id='summary'><pre>
s.cc
 # OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
 # as the occasion calls for it.
 AM_CXXFLAGS = \
+	-std=gnu++98 \
 	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
 	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
 	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS)
diff --git a/libstdc++-v3/src/c++98/Makefile.in b/libstdc++-v3/src/c++98/Makefile.in
index 3c69791bb66..ce86136906b 100644
--- a/libstdc++-v3/src/c++98/Makefile.in
+++ b/libstdc++-v3/src/c++98/Makefile.in
@@ -421,6 +421,7 @@ PARALLEL_FLAGS = -D_GLIBCXX_PARALLEL
 # OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
 # as the occasion calls for it.
 AM_CXXFLAGS = \
+	-std=gnu++98 \
 	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
 	$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
 	$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS)