LLVM currently emits `.note.GNU-stack` sections on all ELF targets.
However, Solaris ld doesn't know/care about them. Even worse, with the
revised Solaris GNU ld patch (D85309 <https://reviews.llvm.org/D85309>),
there are hundreds of warnings:
/usr/gnu/bin/ld: warning: /usr/lib/amd64/crtn.o: missing .note.GNU-stack
section implies executable stack
/usr/gnu/bin/ld: NOTE: This behaviour is deprecated and will be removed
in a future version of the linker
The Solaris crts are not going to change here, and even if they were, GNU
ld would emit `PT_GNU_STACK` segments that Solaris `ld.so.1` ignores.
So the note sections are completely useless on Solaris and this patch
disables their creation.
Instead, Solaris has its own mechanisms to control stack executability:
`PT_SUNW_STACK`, `DT_SUNW_SX_NXSTACK` and the system-wide control via
`sxadm` where `nxstack` defaults to on.
Tested on `amd64-pc-solaris2.11` and `sparcv9-sun-solaris2.11` with Solaris
ld and GNU ld, and `x86_64-pc-linux-gnu`.
Differential Revision: https://reviews.llvm.org/D159179
