[VITA] Add missing chdir and getcwd stubs

Makefile.common

@@ -14,6 +14,7 @@ endif
 # EMULib sound, console, and other utility functions
 SOURCES_C := \
 	$(CORE_DIR)/libretro.c \
+	$(CORE_DIR)/Missing.c \
 	$(EMULIB)/EMULib.c \
 	$(EMULIB)/Sound.c \
 	$(FMSXDIR)/MSX.c \

Missing.c

+#if defined( VITA ) || defined( __CELLOS_LV2__ )
+
+#include <stddef.h>
+
+char* getcwd( char* buf, size_t size )
+{
+  if ( buf != NULL && size >= 2 )
+  {
+    buf[ 0 ] = '.';
+    buf[ 1 ] = 0;
+    return buf;
+  }
+
+  return NULL;
+}
+
+int chdir( const char* path)
+{
+  return 0;
+}
+
+#endif

Missing.h

+#if defined( VITA ) || defined( __CELLOS_LV2__ )
+#include <stddef.h>
+char* getcwd( char* buf, size_t size );
+int chdir( const char* path);
+#endif

libretro.c

@@ -32,6 +32,7 @@ static uint16_t XPal0;
 #define XBuf image_buffer
 #define WBuf image_buffer
 #include "CommonMux.h"
+#include "Missing.h"
 
 uint8_t XKeyState[20];
 #define XKBD_SET(K) XKeyState[Keys[K][0]]&=~Keys[K][1]