[tlbuild] dvisvgm

[Bob Tennent]

 >|> So you're using a relatively recent gcc on a relatively ancient
 >|> Centos-5 system. Can I ask why this combination is appropriate?
 >|
 >|Recent gcc is required because there is some code in TL that doesn't
 >|compile with older compiler. Notable examples include LuaJIT and ICU,
 >|but there might be other "black sheep". (I'm not sure what is the
 >|minimum version of GCC this year, but last year Karl reported that at
 >|least gcc 4.6 was needed.)
 >|
 >|Old linux is required because binaries compiled on the lastest linux
 >|wouldn't work on an older one. (More specifically I think this has to
 >|do with LIBC version rather than with linux version, but in principle
 >|binaries from newer linuxes won't work on older ones.)

Thanks. So to provide a dvisvgm binary with-libgs for Linux users,
it would be best to build on, say, Centos-5, using any gcc that
succeeds. In fact, stock gcc-4.1.2 succeeds and the resulting binary
works at least on Centos-5, Centos-6 and Fedora-20.

But here's what I find surprising: I can apparently build all of TL
(all tests passed) with stock gcc-4.4.7 on Centos-6. Now of course
most of those binaries don't work on, say, Centos-5 (though dvisvgm
does), so perhaps gcc-4.8.2 is now overkill. 

Bob T.