Description of problem:
Firefox in Fedora is built with PGO/LTO enabled. Gdb fails to extract debuginfo from it (perhaps?) and crashes:

extracting debug info from /builddir/build/BUILDROOT/firefox-64.0-5.fc29.x86_64/usr/lib64/firefox/liblgpllibs.so
../../gdb/dwarf2read.c:9730: internal-error: void dw2_add_symbol_to_list(symbol*, pending**): Assertion `(*listhead) == NULL || (SYMBOL_LANGUAGE ((*listhead)->symbol[0]) == SYMBOL_LANGUAGE (symbol))' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) [answered Y; input not from terminal]
BUILDSTDERR: This is a bug, please report it.  For instructions, see:
BUILDSTDERR: <http://www.gnu.org/software/gdb/bugs/>.
../../gdb/dwarf2read.c:9730: internal-error: void dw2_add_symbol_to_list(symbol*, pending**): Assertion `(*listhead) == NULL || (SYMBOL_LANGUAGE ((*listhead)->symbol[0]) == SYMBOL_LANGUAGE (symbol))' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.


Version-Release number of selected component (if applicable):
gdb-8.2-5.fc29.x86_64

Steps to Reproduce:
1. get firefox-64.0-5 from https://koji.fedoraproject.org/koji/taskinfo?taskID=31808300
2. rpmbuild -ba firefox
3. see the crash in build log

Actual results:
Full build log:
https://kojipkgs.fedoraproject.org//work/tasks/8300/31808300/build.log