[build] Honor --disable-symvers (PR bootstrap/48135)

[Paolo Bonzini]

On 03/21/2011 12:34 PM, Rainer Orth wrote:
> Prompted by PR bootstrap/48135, I found that only libstdc++-v3 honors
> --disable-symvers.  The following patch corrects this, but also notices
> again the mess we've created by having at least 3 different sets of
> checks for symbol versioning, each with its own variations ;-(  But this
> is not the time to correct this (yet).
>
> Tested by a i386-pc-solaris2.11 bootstrap and checking that all
> libraries were still versioned by default.  Then I removed and
> configured/built the affected libraries again and checked that
> versioning was correctly disabled.
>
> The patch below was created with -w to hide indentation changes.
>
> Ok for mainline now and perhaps 4.6.1?

Ok for 4.7, RMs should decide about 4.6.1.

Paolo