turn off newer RELX relocation optimizations

[m4b]

otherwise breaks the link step on systems with an older linker (i.e., travis CI, some ubuntu's, etc.). ref rust-lang/rust#34978

We may only want to add this flag on nightly? Not sure how to do that...

NB requires a newer assembler (don't know exact minimal working version), but

as -version
GNU assembler (GNU Binutils) 2.26.0.20160501

works.

[rust-highfive]

r? @brson

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[alexcrichton]

Thanks! We shouldn't have to worry about the assembler version here as we're in control of it, but I think we'll also need to pass this to the build system, right? I remember the error being with jemalloc as well I think...

[alexcrichton]

Ok, I've pushed this as alexcrichton/rust-slave-linux:2016-08-01, it should go out the next time we restart the buildbots. Do you want to send a patch to set this for the musl target as well?

[m4b]

@alexcrichton I thought this was the musl target?

and yea, will need to pass to the build system, as the relocs show up in libstd and liballoc_jemalloc, as well as libunwind (but I hope it's cmake will obey the CFLAGS var?).

Unfortunately I'm not familiar with that part of building rust, and don't know if we have an equivalent CFLAGS somewhere in the pipeline?

[alexcrichton]

Yeah it should be easy enough to modify the mk/cfg/*.mk files and also just add custom flags in src/bootstrap for the rustbuild build system. Also yeah this should only affect musl, and I think in the build system we only need to really worry about jemalloc, other pieces are fine to ignore I think.

[alexcrichton]

Ok, new image is now deployed