Cleanups for the Mac error dialog, after a code review from tma.

- Don't expose the function in sys_local.h (it would be static if we could).
- Don't call it Sys_Cocoa_*; it'd be nonsense with q3a's naming conventions.

code/sys/sys_cocoa.m

@@ -29,7 +29,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 #import <Cocoa/Cocoa.h>
 
-void Sys_Cocoa_MsgBox( const char *text )
+void Cocoa_MsgBox( const char *text )
 {
 	NSRunInformationalAlertPanel(@"ioquake3", 
 	                             [NSString stringWithUTF8String:text],

code/sys/sys_local.h

@@ -46,7 +46,6 @@ unsigned int CON_LogRead( char *out, unsigned int outSize );
 
 #ifdef MACOS_X
 char *Sys_StripAppBundle( char *pwd );
-void Sys_Cocoa_MsgBox( const char *text );
 #endif
 
 void Sys_GLimpSafeInit( void );

code/sys/sys_unix.c

@@ -511,8 +511,10 @@ void Sys_ErrorDialog( const char *error )
 	Sys_Print( va( "%s\n", error ) );
 
 #if defined(MACOS_X) && !DEDICATED
+	/* This function has to be in a separate file, compiled as Objective-C. */
+	extern void Cocoa_MsgBox( const char *text );
 	if (!com_dedicated || !com_dedicated->integer)
-		Sys_Cocoa_MsgBox(error);
+		Cocoa_MsgBox(error);
 #endif
 
 	/* make sure the write path for the crashlog exists... */