Fix memory leaks.

examples/custom_decoder.c

@@ -38,6 +38,7 @@ static ma_result ma_decoding_backend_init__libvorbis(void* pUserData, ma_read_pr
 
     result = ma_libvorbis_init(onRead, onSeek, onTell, pReadSeekTellUserData, pConfig, pAllocationCallbacks, pVorbis);
     if (result != MA_SUCCESS) {
+        ma_free(pVorbis, pAllocationCallbacks);
         return result;
     }
 
@@ -60,6 +61,7 @@ static ma_result ma_decoding_backend_init_file__libvorbis(void* pUserData, const
 
     result = ma_libvorbis_init_file(pFilePath, pConfig, pAllocationCallbacks, pVorbis);
     if (result != MA_SUCCESS) {
+        ma_free(pVorbis, pAllocationCallbacks);
         return result;
     }
 
@@ -113,6 +115,7 @@ static ma_result ma_decoding_backend_init__libopus(void* pUserData, ma_read_proc
 
     result = ma_libopus_init(onRead, onSeek, onTell, pReadSeekTellUserData, pConfig, pAllocationCallbacks, pOpus);
     if (result != MA_SUCCESS) {
+        ma_free(pOpus, pAllocationCallbacks);
         return result;
     }
 
@@ -135,6 +138,7 @@ static ma_result ma_decoding_backend_init_file__libopus(void* pUserData, const c
 
     result = ma_libopus_init_file(pFilePath, pConfig, pAllocationCallbacks, pOpus);
     if (result != MA_SUCCESS) {
+        ma_free(pOpus, pAllocationCallbacks);
         return result;
     }