Kbuild.include: addtree: Remove quotes before matching path

Kbuild.include: addtree: Remove quotes before matching path

systemtap currently fails to build modules when the kernel source and
object trees are separate.

systemtap adds something like -I"/usr/share/systemtap/runtime" to
EXTRA_CFLAGS, and addtree should not adjust this as it's specifying an
absolute directory.  But since make has no understanding of shell
quoting, it does anyway.

For a long time this didn't matter, because addtree would still emit
the original -I option after the adjusted one.  However, commit
db547ef19064 ("Kbuild: don't add obj tree in additional includes")
changed it to remove the original -I option.

Remove quotes (both double and single) before matching against the
excluded patterns.

References: https://bugs.debian.org/856474
Reported-by: Jack Henschel <jackdev@mailbox.org>
Reported-by: Ritesh Raj Sarraf <rrs@debian.org>
Fixes: db547ef19064 ("Kbuild: don't add obj tree in additional includes")
Cc: stable@vger.kernel.org # 4.8+
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name kbuild-include-addtree-remove-quotes-before-matching-path.patch