Hello,

After commit [1] ("Redefine NULL to nullptr"), building gcc
fails when $CXX_FOR_BUILD is not using C++11 mode by default.
This happens with gcc-4.8 which is still supported.

This patch fixes this by adding -std=c++11 or its equivalent
to $CXX_FOR_BUILD using AX_CXX_COMPILE_STDCXX(11).

Tested by successful cross native build for aarch64-none-linux-gnu target.

OK for trunk?


ChangeLog:

2020-08-20  Ilya Leoshkevich  <iii@linux.ibm.com>
            Vasee Vinayagamoorthy  <vaseeharan.vinayagamoorthy@arm.com>

	PR target/95700
	* configure: Regenerate.
	* configure.ac: Require C++11 for building code generation tools.

Regards
Vasee Vinayagamoorthy


PS: I do not have commit rights, therefore could I request
someone to commit it on my behalf if this patch is approved.
Thanks in advance.

[1] https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=d59a576b8b5e12c3a56f0262912090e2921f5daa