I'd guess you are building BLFS 6.3 on top of LFS 6.4 ??
It is a good idea to tell what you are using, every time
a question is asked.
Mesa 6.5.2 is old ( year 2006 ) and will probably compile
with gcc 4.1.x . No reason it should be fixed to be compiled
with anything much newer.
Solution : install (build) an older gcc or uncomment all
"s3" stuff. Or use a newer Mesa, if possible.
You can have as many different compilers, as you want.
example command: 'CC=/usr/local/bin/gcc-4.1.2 .
( Be careful if installing extra gcc in /usr/, libgcc**
can be overwritten, /usr/local/ or /home/ is better )
How is this issue handled by others, building BLFS ??
Suggest : try asking BLFS ...