tmux should not set PKG_CONFIG_PATH (#4901)

* fixes #967

* Version bump to 0.9.1

- Bugfixes for spack find
- 0.9.1 can read specs from current develop.

* Don't assume spack is in the path when building docs.

* Remove PKG_CONFIG_PATH from tmux configure

* Change tmux to AutotoolsPackage

* Correct link to libtinfo in tmux

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

@@ -25,7 +25,7 @@
 from spack import *
 
 
-class Tmux(Package):
+class Tmux(AutotoolsPackage):
     """Tmux is a terminal multiplexer.
 
     What is a terminal multiplexer? It lets you switch easily between several
@@ -45,15 +45,5 @@ class Tmux(Package):
     depends_on('libevent')
     depends_on('ncurses')
 
-    def install(self, spec, prefix):
-        pkg_config_path = ':'.join([
-            spec['libevent'].prefix,
-            spec['ncurses'].prefix
-        ])
-
-        configure(
-            "--prefix=%s" % prefix,
-            "PKG_CONFIG_PATH=%s" % pkg_config_path)
-
-        make()
-        make("install")
+    def configure_args(self):
+        return ['LIBTINFO_LIBS=-lncurses']