BaseTools: CommonLib Fix Crash to write the last byte

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

BaseTools/Source/C/Common/PcdValueCommon.c

@@ -335,7 +335,7 @@ Returns:
       printf("%x\n", Byte);
       Value = End + 1;
     }
-    Buffer = malloc(*Size);
+    Buffer = malloc(*Size + 1);
     if (Buffer == NULL) {
       *Size = 0;
       return NULL;