www/hiawatha: Unbreak build with XSLT=off

${LOCALBASE}/include is implicitly added to the search path when
Hiawatha is built with XSLT=on. Without it the system mbed TLS
headers cannot be found anymore. Add USES=localbase:ldflags to the
MBDEDTLS option to work around this.

src/filehashes.c:27:10: fatal error: 'mbedtls/sha256.h' file not found
#include "mbedtls/sha256.h"

^~~~~~~~~~~~~~~~~~

• While here reset maintainer and take maintainership after the third consecutive timeout

PR: 224156
Reported by: Ross McKelvie <ross@exitzero.uk>
Approved by: portmaster@BSDforge.com (maintainer timeout, 2 weeks)