Fix CentOS 7 RPM build failures. (#7993)

* Correct date in RPM spec file changelog.

2020-01-01 was a Wednesday, not a Thursday.

* Don't mark go.d.plugin executable in staging area.

This prevents it from being checked for C-style debug info that it
doesn't have, thus allowing the build to continue correctly.

netdata.spec.in

@@ -395,7 +395,7 @@ install_go() {
 	return 0
 }
 install_go
-install -m 0750 -p go.d.plugin "${RPM_BUILD_ROOT}%{_libexecdir}/%{name}/plugins.d/go.d.plugin"
+install -m 0640 -p go.d.plugin "${RPM_BUILD_ROOT}%{_libexecdir}/%{name}/plugins.d/go.d.plugin"
 
 %pre
 
@@ -517,7 +517,7 @@ are sensor monitoring, system event monitoring, power control, and serial-over-L
 %attr(4750,root,netdata) %{_libexecdir}/%{name}/plugins.d/freeipmi.plugin
 
 %changelog
-* Thu Jan 01 2020 Austin Hemmelgarn <austin@netdata.cloud> 0.0.0-12
+* Wed Jan 01 2020 Austin Hemmelgarn <austin@netdata.cloud> 0.0.0-12
 - Add explicit installation of log and cache directories
 - Clean up build dependencies.
 * Thu Dec 19 2019 Austin Hemmelgarn <austin@netdata.cloud> 0.0.0-11