lnav: fix head build

Author: tstack

Formula/l/lnav.rb

@@ -40,6 +40,7 @@ class Lnav < Formula
   uses_from_macos "zlib"
 
   def install
+    system "./autogen.sh" if build.head?
     system "./configure", "--with-sqlite3=#{Formula["sqlite"].opt_prefix}",
                           "--with-libarchive=#{Formula["libarchive"].opt_prefix}",
                           *std_configure_args