__strcmp_sse2_unaligned ()
at ../sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S:31
31 ../sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S: No such file or directory.
It means to achieve strcmp x86 assembler file (.S) on 64-bit architectures. In the absence of this implementation file on your system, so gdb complains that it can not access it.