dump_syms generated duplicate CFI data

[GoogleCodeExporter]

I can take this one.

From: https://bugzilla.mozilla.org/show_bug.cgi?id=637665

When running minidump_stack, one can see a lot of log entries like:
range_map-inl.h:91: INFO: StoreRange failed, an existing range contains or 
extends higher than the new range: new 0x222440+0x2, existing 0x222440+0x2

Apparently, this is due to a lot of STACK CFI entries being repeated in the 
.sym files.
For example, taking the last nightly libxul.so.sym:
http://symbols.mozilla.org/firefox/libxul.so/65C7FFCA13C8DFD82F235C4BAA965EB30/l
ibxul.so.sym
$ grep ^STACK libxul.so.sym  | sort | uniq -c | sort -n | awk '{print $1}' | 
uniq -c | tail -10
      1 133
     14 138
      3 139
     37 156
      1 192
      1 262
      1 275
     17 430
      1 434
     16 467

This awful command line displays the number (#1) of single lines that are 
repeated #2 times.
e.g. the last line reads: 16 lines are repeated 467 times.

Original issue reported on code.google.com by thestig@chromium.org on 14 Sep 2011 at 1:06

[GoogleCodeExporter]

I no longer see this problem with a recent Chrome build. I'm not sure if we 
actually fixed this in Breakpad or if the toolchain has changed.

Original comment by thestig@chromium.org on 19 Dec 2013 at 1:41