build robustness/reproducibility fixes for the mruby flavour of www/h2o

- building the mruby part of this uses autoconf in an otherwise cmake-based
port build, so it can't use the normal ports infrastructure which passes in
autoconf cache variables to prevent it from finding gawk/ggred/gsed/gmkdir
during the build. pass in the necessary variables by MAKE_ENV instead.

- building mruby uses the static oniguruma library from ports if found at
build time, otherwise builds its own bundled version. add BUILD_DEPENDS
to make sure the ports version of oniguruma is found.

problem reported by tb@, ok tb@ please commit otto@

www/h2o/Makefile

@@ -8,7 +8,7 @@ CATEGORIES =	www
 GH_ACCOUNT =	h2o
 GH_PROJECT =	h2o
 GH_TAGNAME =	v2.2.6
-REVISION =	6
+REVISION =	7
 
 HOMEPAGE =	https://h2o.examp1e.net/
 MAINTAINER =	Otto Moerbeek <otto@drijf.net>
@@ -42,6 +42,13 @@ CONFIGURE_ARGS =	-DBUILD_SHARED_LIBS=ON \
 MODULES +=		lang/ruby
 MODRUBY_RUNDEP =	No
 CONFIGURE_ARGS +=	-DWITH_MRUBY=ON
+# mruby build picks up the static oniguruma library if present during build
+# otherwise uses a bundled older version
+BUILD_DEPENDS +=	textproc/oniguruma
+MAKE_ENV +=		AWK=/usr/bin/awk \
+			SED=/usr/bin/sed \
+			GREP=/usr/bin/grep \
+			ac_cv_path_mkdir=/bin/mkdir
 
 pre-configure:
 	ln -sf ${RUBY} ${WRKDIR}/bin/ruby