Add compiler:c++11-lang to USES to fix build on GCC-bsed systems:

  Could NOT find Boost (missing: Boost_INCLUDE_DIR filesystem system) (Required is at least version "1.35")

Approved by:	portgmr (tier-2 blanket)


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@530550 35697150-7ecd-e111-bb59-0022644237b5

devel/volk/Makefile

@@ -13,7 +13,7 @@ LICENSE=	GPLv3
 LIB_DEPENDS=	liborc-0.4.so:devel/orc
 BUILD_DEPENDS=	${PYTHON_SITELIBDIR}/mako/__init__.py:textproc/py-mako@${PY_FLAVOR}
 
-USES=		cmake python:3.5+
+USES=		cmake compiler:c++11-lang python:3.5+
 
 USE_GITHUB=	yes
 GH_ACCOUNT=	gnuradio