fix building with new gcc (#1423306)

conky-gcc7.patch

@@ -0,0 +1,11 @@
+diff -up conky-1.10.4/src/luamm.hh.gcc7 conky-1.10.4/src/luamm.hh
+--- conky-1.10.4/src/luamm.hh.gcc7	2017-02-20 15:21:51.061823560 +0100
++++ conky-1.10.4/src/luamm.hh	2017-02-20 15:21:59.622742073 +0100
+@@ -26,6 +26,7 @@
+ #include <memory>
+ #include <mutex>
+ #include <stdexcept>
++#include <functional>
+ 
+ #include <lua.hpp>
+ 

conky.spec

@@ -25,6 +25,7 @@ Group:          User Interface/X
 License:        GPLv3+
 URL:            https://github.com/brndnmtthws/conky
 Source0:        https://github.com/brndnmtthws/%{name}/archive/v%{version}/%{name}-%{version}.tar.gz
+Patch1:         conky-gcc7.patch
 
 BuildRequires:  libXft-devel
 BuildRequires:  libXt-devel
@@ -53,6 +54,7 @@ It just keeps on given'er. Yeah.
 
 %prep
 %setup -q
+%patch1 -p1 -b .gcc7
 
 # remove -Werror from CFLAGS
 sed -i 's|-Werror||' cmake/ConkyBuildOptions.cmake