MAINT-5232: Make LLError::is_available() depend on both LLSingletons.

LLError machinery depends on two different LLSingletons. Its is_available()
function is primarily for LLSingleton itself to determine whether it is, or is
not, safe to log. Until both of LLError's LLSingletons have been constructed,
attempting to log LLSingleton operations could produce infinite recursion.

indra/llcommon/llerror.cpp

@@ -414,11 +414,6 @@ namespace
 
 namespace LLError
 {
-	bool is_available()
-	{
-		return Globals::instanceExists();
-	}
-
 	class SettingsConfig : public LLRefCount
 	{
 		friend class Settings;
@@ -458,7 +453,7 @@ namespace LLError
 		Settings();
 
 		SettingsConfigPtr getSettingsConfig();
-	
+
 		void reset();
 		SettingsStoragePtr saveAndReset();
 		void restore(SettingsStoragePtr pSettingsStorage);
@@ -466,7 +461,7 @@ namespace LLError
 	private:
 		SettingsConfigPtr mSettingsConfig;
 	};
-	
+
 	SettingsConfig::SettingsConfig()
 		: LLRefCount(),
 		mPrintLocation(false),
@@ -501,26 +496,31 @@ namespace LLError
 	{
 		return mSettingsConfig;
 	}
-	
+
 	void Settings::reset()
 	{
 		Globals::getInstance()->invalidateCallSites();
 		mSettingsConfig = new SettingsConfig();
 	}
-	
+
 	SettingsStoragePtr Settings::saveAndReset()
 	{
 		SettingsStoragePtr oldSettingsConfig(mSettingsConfig.get());
 		reset();
 		return oldSettingsConfig;
 	}
-	
+
 	void Settings::restore(SettingsStoragePtr pSettingsStorage)
 	{
 		Globals::getInstance()->invalidateCallSites();
 		SettingsConfigPtr newSettingsConfig(dynamic_cast<SettingsConfig *>(pSettingsStorage.get()));
 		mSettingsConfig = newSettingsConfig;
 	}
+
+	bool is_available()
+	{
+		return Settings::instanceExists() && Globals::instanceExists();
+	}
 }
 
 namespace LLError