Optimise away eh_frame advance_loc 0

[Jeff Law]

On 10/28/19 10:16 AM, Joseph Myers wrote:
> This breaks the build of glibc for sh4-linux-gnu (confirmed this is the 
> revision that introduces the breakage) and mips64-linux-gnu (not tested 
> the specific revisions, but the symptoms are the same so it looks like 
> the same breakage).
> 
> https://sourceware.org/ml/libc-testresults/2019-q4/msg00129.html
> 
> I've attached malloc.s (gzipped) from an sh4-linux-gnu glibc build.  The 
> symptom is:
> 
> $ sh4-glibc-linux-gnu-as -little -o malloc.o malloc.s
> malloc.s: Assembler messages:
> malloc.s: Fatal error: can't write -1 bytes to section .debug_frame of malloc.o: 'bad value'
> 
> (and binutils commit 6f69abb0498286297936a178ba81c7e445aa4437 fails while 
> the previous commit passes).
> 
I'm seeing this across a variety of architectures in my tester as well.

jeff