On i386 and armhf __libc_do_syscall might be used to invoke a syscall.
Replace __libc_do_syscall with "in syscall ..." and filter out
possible extra (assembly) source file lines containing
libc-do-syscall.S from the gdb output.
https://bugs.kde.org/show_bug.cgi?id=502126
(cherry picked from commit
ddcb3aa3ed3188cd28c193225245a76e928b850b)
# in __syscall_cancel_arch is just in a syscall
s/in __syscall_cancel_arch .*/in syscall .../
+# do_syscall is in syscall
+s/__libc_do_syscall ().*/0x........ in syscall .../
+
+# extra source code line
+/libc-do-syscall.S/d
+
# anonymise kill syscall.
s/in kill ().*$/in syscall .../