[v3] use -Wl,-z,relro if possible

[Paolo Carlini]

Benjamin Kosnik wrote:

>>However, the new configure test is not yet sufficiently strong to 
>>disable the use of gc-sections on my binutils2.16.1 system. I'm 
>>available to test further improvements to the configure tests, if you 
>>like (remember our timezones, though ;)
>>    
>>
>Ok. Here, try this one. I'm just guessing, at this point. 
>  
>
Ok, before going to sleep I have time to test it. However, I fear this
specific issue is even more subtle, because, as you can see from the
posted testresults, for example, here (unix/-m32):

    http://gcc.gnu.org/ml/gcc-testresults/2006-01/msg00808.html

it's not that *every* testcase fails, only *many* of them. We should
find a pattern, characterizing those failing tests, and reduce it to an
autoconf test... Nothing obvious to me :-(

Paolo.