add new package: lmbench (#15457)

* add new package: lmbench

* refine LDFLAGS append call

var/spack/repos/builtin/packages/lmbench/package.py

+# Copyright 2013-2020 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class Lmbench(MakefilePackage):
+    """lmbench is a suite of simple, portable, ANSI/C microbenchmarks for
+    UNIX/POSIX. In general, it measures two key features: latency and
+    bandwidth. lmbench is intended to give system developers insight into
+    basic costs of key operations."""
+
+    homepage = "http://lmbench.sourceforge.net/"
+    git      = "https://github.com/intel/lmbench.git"
+
+    version('master', branch='master')
+
+    depends_on('libtirpc')
+
+    def setup_build_environment(self, env):
+        env.prepend_path('CPATH', self.spec['libtirpc'].prefix.include.tirpc)
+        env.append_flags('LDFLAGS', '-ltirpc')
+
+    def build(self, spec, prefix):
+        make('build')
+
+    def install(self, spec, prefix):
+        install_tree('.', prefix)