Refactor for testing

Added basic decoding functionality to test.

Refactored some code to stop 3DS specific code from compiling on
GNU/Linux.

Tested working by running the test executable on GNU/Linux. Vorbis
decoding has many errors detected by valgrind (but still decodes
successfully).
Opus, flac, and mp3 decoding work without errors.

Signed-off-by: Mahyar Koshkouei <mk@deltabeard.com>

source/file.h

@@ -0,0 +1,25 @@
+enum file_types
+{
+	FILE_TYPE_ERROR = 0,
+	FILE_TYPE_WAV,
+	FILE_TYPE_FLAC,
+	FILE_TYPE_VORBIS,
+	FILE_TYPE_OPUS,
+	FILE_TYPE_MP3
+};
+
+/**
+ * Obtain file type string from file_types enum.
+ *
+ * \param	ft	File type enum.
+ * \return		String representation of enum.
+ */
+const char* fileToStr(enum file_types ft);
+
+/**
+ * Obtains file type.
+ *
+ * \param	file	File location.
+ * \return			file_types enum or 0 on error and errno set.
+ */
+enum file_types getFileType(const char *file);