liblzma: Fix incorrect function type error from sanitizer

Clang 17 with -fsanitize=address,undefined:

    src/liblzma/common/filter_common.c:366:8: runtime error:
        call to function encoder_find through pointer to incorrect
        function type 'const lzma_filter_coder *(*)(unsigned long)'
    src/liblzma/common/filter_encoder.c:187: note:
        encoder_find defined here

Use a wrapper function to get the correct type neatly.
This reduces the number of casts needed too.

This issue could be a problem with control flow integrity (CFI)
methods that check the function type on indirect function calls.

Fixes: 3b34851de1

src/liblzma/common/filter_decoder.c

@@ -150,6 +150,16 @@ decoder_find(lzma_vli id)
 }
 
 
+// lzma_filter_coder begins with the same members as lzma_filter_decoder.
+// This function is a wrapper with a type that is compatible with the
+// typedef of lzma_filter_find in filter_common.h.
+static const lzma_filter_coder *
+coder_find(lzma_vli id)
+{
+	return (const lzma_filter_coder *)decoder_find(id);
+}
+
+
 extern LZMA_API(lzma_bool)
 lzma_filter_decoder_is_supported(lzma_vli id)
 {
@@ -162,7 +172,7 @@ lzma_raw_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
 		const lzma_filter *options)
 {
 	return lzma_raw_coder_init(next, allocator,
-			options, (lzma_filter_find)(&decoder_find), false);
+			options, &coder_find, false);
 }
 
 
@@ -181,8 +191,7 @@ lzma_raw_decoder(lzma_stream *strm, const lzma_filter *options)
 extern LZMA_API(uint64_t)
 lzma_raw_decoder_memusage(const lzma_filter *filters)
 {
-	return lzma_raw_coder_memusage(
+	return lzma_raw_coder_memusage(&coder_find, filters);
-			(lzma_filter_find)(&decoder_find), filters);
 }
 
 

src/liblzma/common/filter_encoder.c

@@ -193,6 +193,16 @@ encoder_find(lzma_vli id)
 }
 
 
+// lzma_filter_coder begins with the same members as lzma_filter_encoder.
+// This function is a wrapper with a type that is compatible with the
+// typedef of lzma_filter_find in filter_common.h.
+static const lzma_filter_coder *
+coder_find(lzma_vli id)
+{
+	return (const lzma_filter_coder *)encoder_find(id);
+}
+
+
 extern LZMA_API(lzma_bool)
 lzma_filter_encoder_is_supported(lzma_vli id)
 {
@@ -232,7 +242,7 @@ lzma_raw_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
 		const lzma_filter *filters)
 {
 	return lzma_raw_coder_init(next, allocator,
-			filters, (lzma_filter_find)(&encoder_find), true);
+			filters, &coder_find, true);
 }
 
 
@@ -240,7 +250,7 @@ extern LZMA_API(lzma_ret)
 lzma_raw_encoder(lzma_stream *strm, const lzma_filter *filters)
 {
 	lzma_next_strm_init(lzma_raw_coder_init, strm, filters,
-			(lzma_filter_find)(&encoder_find), true);
+			&coder_find, true);
 
 	strm->internal->supported_actions[LZMA_RUN] = true;
 	strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
@@ -253,8 +263,7 @@ lzma_raw_encoder(lzma_stream *strm, const lzma_filter *filters)
 extern LZMA_API(uint64_t)
 lzma_raw_encoder_memusage(const lzma_filter *filters)
 {
-	return lzma_raw_coder_memusage(
+	return lzma_raw_coder_memusage(&coder_find, filters);
-			(lzma_filter_find)(&encoder_find), filters);
 }