Fix render failing to compile with GCC 11

Due to Client::SetPref not being available for use by AddCustomGol. GCC 7 didn't mind this, weird.

ignore/valgrind.supp

@@ -0,0 +1,10 @@
+{
+   luajit_str_fastcmp_uninit_cond
+   Memcheck:Cond
+   obj:/usr/lib/libluajit-5.1.so.2.0.5
+}
+{
+   fftw_crap_access
+   Memcheck:Addr16
+   obj:/usr/lib/libfftw3f.so.3.6.10
+}

src/simulation/GOLString.cpp

@@ -95,6 +95,7 @@ String SerialiseGOLRule(int rule)
 	return golName.Build();
 }
 
+#ifndef RENDERER
 bool AddCustomGol(String ruleString, String nameString, unsigned int highColor, unsigned int lowColor)
 {
 	auto customGOLTypes = Client::Ref().GetPrefByteStringArray("CustomGOL.Types");
@@ -121,3 +122,4 @@ bool AddCustomGol(String ruleString, String nameString, unsigned int highColor,
 	Client::Ref().SetPref("CustomGOL.Types", newCustomGOLTypes);
 	return true;
 }
+#endif