This patch tackles two issues:
- GHC stores a "link info" string into a ELF section. Initially a section with type "note" was used but GHC didn't follow the ELF specification which specifies a record-based format for these sections. With D1375 we switched to a "progbits" section type for which there isn't any format constraint. This is an issue for D1242 which use GCC's --gc-sections which collects "unused" sections, such as our section containing link info... In this patch, we fall back to a section with type "note" but we respect the specified format.
- Reading back the ELF section was done by parsing the result of a call to "readelf". Calling readelf is problematic because the program may not be available or it may be renamed on some platforms (see D1326). Moreover we have no garanty that its output layout will stay the same in future releases of readelf. Finally we would need to fix the parsing to support "note" sections because of 1. Instead, this patch proposes to use Data.Binary.Get to directly read the "link info" note into its section. ELF has a specification, hence it should work on every conforming platform.