[Bug lto/63546] ICE: Segmentation fault in lto_get_decl_name_mapping on ppc64

[hubicka at ucw dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63546

--- Comment #7 from Jan Hubicka <hubicka at ucw dot cz> ---
Here we die because we do not have variable constructor in LTO stream because
the variable was optimized out at compile time already.  Do we still need to
build RTL here?  We can easily check for optimized out vars...

But if we need a placeholder RTL, I suppose most practical variant would be
to avoid get_variable_section from ICEing for those optimized out vars and
just assume something (it is all about decision whether the var will be in 
rodata/rodata.rel or rodata.rel.local - definitely not relevant for dwarf2out)