Individualize NameHashSet Hashing & Revisit #709 (#740)

* Make mac/win lookups lowercase'd

* Revert #709 & 81042cc

* Adjust HashPolicy implementation across sourcemod

Basically, in order to implement our own (actual) hash policy in
`PluginSys.h`, we needed to remove the blanket implementation of `hash`
that was used before. Now, each policy must implement `hash` along with
`matches` in order to be used with `NameHashSet`. While this does force
us to change every implementation of policies across the entirety of
sourcemod, it allows core to use flexible implementations of `hash`.

* Remove logic duplication

* Improve lowercase checks

core/logic/PluginSys.cpp

@@ -31,7 +31,6 @@
 
 #include <stdio.h>
 #include <stdarg.h>
-#include <ctype.h>
 #include "PluginSys.h"
 #include "ShareSys.h"
 #include <ILibrarySys.h>
@@ -47,7 +46,6 @@
 #include "frame_tasks.h"
 #include <amtl/am-string.h>
 #include <amtl/am-linkedlist.h>
-#include <amtl/am-uniqueptr.h>
 #include <bridge/include/IVEngineServerBridge.h>
 #include <bridge/include/CoreProvider.h>
 
@@ -934,38 +932,16 @@ void CPluginManager::LoadPluginsFromDir(const char *basedir, const char *localpa
 	libsys->CloseDirectory(dir);
 }
 
-#if defined PLATFORM_WINDOWS || defined PLATFORM_APPLE
-char *strdup_tolower(const char *input)
-{
-	char *str = strdup(input);
-	
-	for (char *c = str; *c; c++)
-	{
-		*c = tolower((unsigned char)*c);
-	}
-	
-	return str;
-}
-#endif
-
 LoadRes CPluginManager::LoadPlugin(CPlugin **aResult, const char *path, bool debug, PluginType type)
 {
 	if (m_LoadingLocked)
 		return LoadRes_NeverLoad;
 
-/* For windows & mac, we convert the path to lower-case in order to avoid duplicate plugin loading */
-#if defined PLATFORM_WINDOWS || defined PLATFORM_APPLE
-	ke::UniquePtr<char> finalPath = ke::UniquePtr<char>(strdup_tolower(path));
-#else 
-	ke::UniquePtr<char> finalPath = ke::UniquePtr<char>(strdup(path));
-#endif
-
-
 	/**
 	 * Does this plugin already exist?
 	 */
 	CPlugin *pPlugin;
-	if (m_LoadLookup.retrieve(finalPath.get(), &pPlugin))
+	if (m_LoadLookup.retrieve(path, &pPlugin))
 	{
 		/* Check to see if we should try reloading it */
 		if (pPlugin->GetStatus() == Plugin_BadLoad
@@ -978,12 +954,11 @@ LoadRes CPluginManager::LoadPlugin(CPlugin **aResult, const char *path, bool deb
 		{
 			if (aResult)
 				*aResult = pPlugin;
-			
 			return LoadRes_AlreadyLoaded;
 		}
 	}
 
-	CPlugin *plugin = CompileAndPrep(finalPath.get());
+	CPlugin *plugin = CompileAndPrep(path);
 
 	// Assign our outparam so we can return early. It must be set.
 	*aResult = plugin;
@@ -2416,4 +2391,4 @@ static OldPluginAPI sOldPluginAPI;
 IPluginManager *CPluginManager::GetOldAPI()
 {
 	return &sOldPluginAPI;
-}
+}