sudo: Fix out of tree builds ${B} != ${S}

The last change to sudo broke out of tree builds, fix this.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
libpcre: Fix BUILD_CFLAGS for out of tree support

The BUILD_CFLAGS were broken since /include no longer exists in this package. We
do need to include ${B} in the include path for pcre.h though.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>