plugin API: use const char* insead of char*

I hope it doesn't change the ABI

v2: fix GSnull/zzogl/zerogs
v3: duplicated code on windows...

common/include/PS2Edefs.h

@@ -241,7 +241,7 @@ extern "C" {
 // basic funcs
 
 s32  CALLBACK GSinit();
-s32  CALLBACK GSopen(void *pDsp, char *Title, int multithread);
+s32  CALLBACK GSopen(void *pDsp, const char *Title, int multithread);
 void CALLBACK GSclose();
 void CALLBACK GSshutdown();
 void CALLBACK GSsetSettingsDir( const char* dir );
@@ -572,7 +572,7 @@ typedef void (CALLBACK* _PS2EsetEmuVersion)(const char* emuId, u32 version);		//
 // GS
 // NOTE: GSreadFIFOX/GSwriteCSR functions CANNOT use XMM/MMX regs
 // If you want to use them, need to save and restore current ones
-typedef s32  (CALLBACK* _GSopen)(void *pDsp, char *Title, int multithread);
+typedef s32  (CALLBACK* _GSopen)(void *pDsp, const char *Title, int multithread);
 typedef s32  (CALLBACK* _GSopen2)( void *pDsp, u32 flags );
 typedef void (CALLBACK* _GSvsync)(int field);
 typedef void (CALLBACK* _GSgifTransfer)(const u32 *pMem, u32 size);

plugins/GSdx/GS.cpp

@@ -179,7 +179,7 @@ EXPORT_C GSclose()
 	}
 }
 
-static int _GSopen(void** dsp, char* title, GSRendererType renderer, int threads = -1)
+static int _GSopen(void** dsp, const char* title, GSRendererType renderer, int threads = -1)
 {
 	GSDevice* dev = NULL;
 
@@ -528,7 +528,7 @@ EXPORT_C_(int) GSopen2(void** dsp, uint32 flags)
 	}
 	stored_toggle_state = toggle_state;
 
-	int retval = _GSopen(dsp, NULL, renderer);
+	int retval = _GSopen(dsp, "", renderer);
 
 	if (s_gs != NULL)
 		s_gs->SetAspectRatio(0);	 // PCSX2 manages the aspect ratios
@@ -538,7 +538,7 @@ EXPORT_C_(int) GSopen2(void** dsp, uint32 flags)
 	return retval;
 }
 
-EXPORT_C_(int) GSopen(void** dsp, char* title, int mt)
+EXPORT_C_(int) GSopen(void** dsp, const char* title, int mt)
 {
 	/*
 	if(!XInitThreads()) return -1;

plugins/GSnull/GS.cpp

@@ -121,7 +121,7 @@ EXPORT_C_(void) GSshutdown()
 	GSLog::Close();
 }
 
-EXPORT_C_(s32) GSopen(void *pDsp, char *Title, int multithread)
+EXPORT_C_(s32) GSopen(void *pDsp, const char *Title, int multithread)
 {
 	int err = 0;
 	GSLog::WriteLn("GS open.");

plugins/GSnull/Linux/GSLinux.cpp

@@ -20,7 +20,7 @@ Display *display;
 int screen;
 GtkScrolledWindow *win;
 
-int GSOpenWindow(void *pDsp, char *Title)
+int GSOpenWindow(void *pDsp, const char *Title)
 {
 	display = XOpenDisplay(0);
 	screen = DefaultScreen(display);

plugins/GSnull/Linux/GSLinux.h

@@ -20,7 +20,7 @@
 #include <X11/Xlib.h>
 #include <X11/keysym.h>
 
-extern int GSOpenWindow(void *pDsp, char *Title);
+extern int GSOpenWindow(void *pDsp, const char *Title);
 extern int GSOpenWindow2(void *pDsp, u32 flags);
 extern void GSCloseWindow();
 extern void GSProcessMessages();

plugins/GSnull/Windows/GSwin.cpp

@@ -34,7 +34,7 @@ LRESULT CALLBACK MsgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
     return 0;
 }
 
-int GSOpenWindow(void *pDsp, char *Title)
+int GSOpenWindow(void *pDsp, const char *Title)
 {
 	WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,
 					GetModuleHandle(NULL), NULL, NULL, NULL, NULL,

plugins/GSnull/Windows/GSwin.h

@@ -18,7 +18,7 @@
 #include <windows.h>
 #include <windowsx.h>
 
-extern int GSOpenWindow(void *pDsp, char *Title);
+extern int GSOpenWindow(void *pDsp, const char *Title);
 extern void GSCloseWindow();
 extern void GSProcessMessages();
 extern void HandleKeyEvent(keyEvent *ev);

plugins/zerogs/dx/GSmain.cpp

@@ -358,7 +358,7 @@ LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam )
 	return DefWindowProc( hWnd, msg, wParam, lParam );
 }
 
-s32 CALLBACK GSopen(void *pDsp, char *Title, int multithread) {
+s32 CALLBACK GSopen(void *pDsp, const char *Title, int multithread) {
 
 	g_GSMultiThreaded = multithread;
 

plugins/zzogl-pg/opengl/GSmain.cpp

@@ -282,7 +282,7 @@ __forceinline void InitMisc()
 	ResetRegs();
 }
 
-EXPORT_C_(s32) GSopen(void *pDsp, char *Title, int multithread)
+EXPORT_C_(s32) GSopen(void *pDsp, const char *Title, int multithread)
 {
 	FUNCLOG