Fixing the build on GNU/Linux. Please report if this breaks the build…

… on other systems. I hope it doesn't.

* "-lpthread" was ignored by GCC resulting in a linking error. Declaring it closer to the other linker parameters fixed the issue.
* There was an #endif misplaced which was improperly including the closing bracket of a switch statement. So when the #ifdef was false, the resulting code would get broken.
* Also the #include "libz/libz.h" was resulting in the header not being found. I switched it to #include <libz.h> so it will look for the file in the system default library include directories.

VGMPlay.c

@@ -51,7 +51,7 @@
 #endif
 #endif
 
-#include "zlib/zlib.h"
+#include <zlib.h>
 
 #include "chips/mamedef.h"
 

VGMPlay_AddFmts.c

@@ -10,7 +10,7 @@
 #ifdef WIN32
 #include <windows.h>
 #endif
-#include "zlib/zlib.h"
+#include <zlib.h>
 
 #include "chips/mamedef.h"
 

chips/sn764intf.c

@@ -92,8 +92,8 @@ void device_stop_sn764xx(UINT8 ChipID)
 	case EC_MAXIM:
 		SN76489_Shutdown((SN76489_Context*)info->chip);
 		break;
-	}
 #endif
+	}
 }
 
 void device_reset_sn764xx(UINT8 ChipID)

makefile

@@ -77,7 +77,7 @@ EMUOBJS = \
 	$(EMUOBJ)/ymz280b.o
 
 VGMPlay:	$(OBJDIRS) $(MAINOBJS) $(EMUOBJS)
-	$(CC) -lpthread $(MAINOBJS) $(EMUOBJS) -lm -lrt -Wl,-lz -o VGMPlay
+	$(CC) $(MAINOBJS) $(EMUOBJS) -lpthread -lm -lrt -Wl,-lz -o VGMPlay
 
 # compile the main c-files
 $(OBJ)/%.o:	$(SRC)/%.c