[gdb/testsuite] Fix regexp in gdb.arch/ftrace-insn-reloc.exp

With test-case gdb.arch/ftrace-insn-reloc.exp and host board
local-remote-host-notty and target board native-gdbserver I run into:
...
(gdb) info sharedlibrary^M
From To    Syms Read   Shared Object Library^M
$hex $hex  Yes         /lib64/ld-linux-x86-64.so.2^M
$hex $hex  Yes         /home/remote-host/libinproctrace.so^M
$hex $hex  Yes         /lib64/libm.so.6^M
$hex $hex  Yes         /lib64/libc.so.6^M
$hex $hex  Yes         /lib64/libdl.so.2^M
$hex $hex  Yes (*)     /usr/lib64/libstdc++.so.6^M
$hex $hex  Yes (*)     /lib64/libgcc_s.so.1^M
$hex $hex  Yes         /lib64/libpthread.so.0^M
(*): Shared library is missing debugging information.^M
(gdb) FAIL: gdb.arch/ftrace-insn-reloc.exp: IPA loaded
...
due to trying to match libinproctrace.so using the target path, while the
command lists it using the host path.

Fix this by making the regexp less strict.

Tested on x86_64-linux.