checkpatch: relax regexp for COMMIT_LOG_LONG_LINE

checkpatch: relax regexp for COMMIT_LOG_LONG_LINE

One exceptions to the COMMIT_LOG_LONG_LINE rule is a file path followed by
:.  That is typically some sort diagnostic message from a compiler or a
build tool, in which case we don't want to wrap the lines but keep the
message unmodified.

The regular expression used to match this pattern currently doesn't accept
absolute paths or + characters.  This can result in false positives as in
the following (out-of-tree) example:

  ...
  /home/jerome/work/optee_repo_qemu/build/../toolchains/aarch32/bin/arm-linux-gnueabihf-ld.bfd: /home/jerome/work/toolchains-gcc10.2/aarch32/bin/../lib/gcc/arm-none-linux-gnueabihf/10.2.1/../../../../arm-none-linux-gnueabihf/lib/libstdc++.a(eh_alloc.o): in function `__cxa_allocate_exception':
  /tmp/dgboter/bbs/build03--cen7x86_64/buildbot/cen7x86_64--arm-none-linux-gnueabihf/build/src/gcc/libstdc++-v3/libsupc++/eh_alloc.cc:284: undefined reference to `malloc'
  ...

Update the regular expression to match the above paths.

Link: https://lkml.kernel.org/r/20210923143842.2837983-1-jerome@forissier.org
Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>