configure - gcc >4.6 needed for JDK9 build

[Mike Burton]

>> On 24 Jan 2017, at 21:25, Kim Barrett <kim.barrett at oracle.com> wrote:
>> 
>> On Jan 23, 2017, at 5:34 AM, Mike Burton <mikeb at mycosystems.co.uk> wrote:
>> 
>> Hello,
>> 
>> I ran an OpenJDK Hack Day session on Saturday, at which some people got stuck on lost a fair bit of time, failing to build JDK9. Then we found that updating gcc from 4.6 to 4.8 fixed it.
>> Could the `configure` script be updated (by running get-source.sh) so as to check for minimum required gcc version?
>> 
>> Best Regards
>> 
>> Mike Burton
> 
> I don’t think there is supposed to be a requirement for gcc > 4.6 in JDK 9.  I’m pretty
> sure there are folks still building with older versions.  It would be helpful to know the
> details of the platform and the error messages that led to the conclusion that something
> more recent was required.

Platform is Ubuntu 14.04, error message below:

=== Output from failing command(s) repeated here ===
* For target hotspot_variant-server_libjvm_gtest_objs_BUILD_GTEST_LIBJVM_link:
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.6/libstdc++.a(ctype.o): relocation R_X86_64_32S against `vtable for std::ctype<wchar_t>' can not be used when making a shared object; recompile with -fPIC
/usr/lib/gcc/x86_64-linux-gnu/4.6/libstdc++.a: could not read symbols: Bad value
collect2: ld returned 1 exit status
=== End of repeated output ===