Replace zlib, zstd, libchdr, libzip and libpng with libretro-common

Deflate, zlib and gzip streams go through rinflate and rdeflate, zstd
through rzstd, CHD images through rchd, zip archives through
rzip_archive and PNG through rpng. The bundled libraries, their build
glue and the system-library options are gone; adler32 and uncompress
keep zlib's ABI for the prebuilt FFmpeg archives that still call them.
libretro-common is one CMake library that the core, the headless tool
and the unit tests all link.

The reads take shorter paths on the way. CHD decodes straight from the
loader's reads and a range of blocks at a time, and a file read at any
alignment decodes into place; CSO keeps one inflate stream instead of
one per block; a plain ISO serves a file read with one read of its exact
bytes; a stored zip member is read in place and a deflated one through
restart points rather than a copy of the whole image in memory; zip
members decode into the caller's buffer; sequential reads through the
frontend's VFS skip the seek, which also keeps its buffering.

libretro/test reads one image as ISO, CSO, CHD and zip through the block
devices, boots each, and checks the codecs against Python-made vectors;
a CI job runs it.

Core/HLE/sceDeflt.cpp

@@ -15,9 +15,10 @@
 // Official git repository and contact information can be found at
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
-#include "zlib.h"
+#include <encodings/crc32.h>
 
 #include "Common/CommonTypes.h"
+#include "Common/Data/Encoding/Compression.h"
 #include "Core/Debugger/MemBlockInfo.h"
 #include "Core/HLE/HLE.h"
 #include "Core/HLE/FunctionWrappers.h"
@@ -35,49 +36,41 @@ static int CommonDecompress(int windowBits, u32 OutBuffer, int OutBufferLength,
 		return hleLogError(Log::HLE, 0, "bad crc32 address");
 	}
 
-	z_stream stream{};
 	u8 *outBufferPtr = Memory::GetPointerWriteOrException(OutBuffer);
-	stream.next_in = (Bytef*)Memory::GetPointerOrException(InBuffer);
+	const u8 *inBufferPtr = Memory::GetPointerOrException(InBuffer);
 	// We don't know the available length, just let it use as much as it wants.
-	stream.avail_in = (uInt)Memory::ClampValidSizeAt(InBuffer, Memory::g_MemorySize);
-	stream.next_out = outBufferPtr;
-	stream.avail_out = (uInt)OutBufferLength;
+	const size_t inAvail = Memory::ClampValidSizeAt(InBuffer, Memory::g_MemorySize);
+	const size_t outAvail = OutBufferLength > 0 ? Memory::ClampValidSizeAt(OutBuffer, (u32)OutBufferLength) : 0;
 
-	int err = inflateInit2(&stream, windowBits);
-	if (err != Z_OK) {
-		return hleLogError(Log::HLE, 0, "inflateInit2 failed %08x", err);
-	}
-	err = inflate(&stream, Z_FINISH);
-	inflateEnd(&stream);
-
-	if (err != Z_STREAM_END) {
-		return hleLogError(Log::HLE, 0, "inflate failed %08x", err);
+	size_t totalIn = 0;
+	const int64_t totalOut = InflateBuffer(windowBits, inBufferPtr, inAvail, outBufferPtr, outAvail, &totalIn);
+	if (totalOut < 0) {
+		return hleLogError(Log::HLE, 0, "inflate failed");
 	}
 	if (crc32Addr.IsValid()) {
-		uLong crc = crc32(0L, Z_NULL, 0);
-		*crc32Addr = crc32(crc, outBufferPtr, stream.total_out);
+		*crc32Addr = encoding_crc32(0, outBufferPtr, (size_t)totalOut);
 	}
 
-	if (MemBlockInfoDetailed(stream.total_in, stream.total_out)) {
+	if (MemBlockInfoDetailed((u32)totalIn, (u32)totalOut)) {
 		char tagData[128];
-		size_t tagSize = FormatMemWriteTagAt(tagData, sizeof(tagData), "sceDeflt/", InBuffer, stream.total_in);
-		NotifyMemInfo(MemBlockFlags::READ, InBuffer, stream.total_in, tagData, tagSize);
-		NotifyMemInfo(MemBlockFlags::WRITE, OutBuffer, stream.total_out, tagData, tagSize);
+		size_t tagSize = FormatMemWriteTagAt(tagData, sizeof(tagData), "sceDeflt/", InBuffer, (u32)totalIn);
+		NotifyMemInfo(MemBlockFlags::READ, InBuffer, (u32)totalIn, tagData, tagSize);
+		NotifyMemInfo(MemBlockFlags::WRITE, OutBuffer, (u32)totalOut, tagData, tagSize);
 	}
 
-	return hleLogDebug(Log::HLE, stream.total_out);
+	return hleLogDebug(Log::HLE, (int)totalOut);
 }
 
 static int sceDeflateDecompress(u32 OutBuffer, int OutBufferLength, u32 InBuffer, u32 Crc32Addr) {
-	return CommonDecompress(-MAX_WBITS, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
+	return CommonDecompress(-15, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
 }
 
 static int sceGzipDecompress(u32 OutBuffer, int OutBufferLength, u32 InBuffer, u32 Crc32Addr) {
-	return CommonDecompress(16 + MAX_WBITS, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
+	return CommonDecompress(31, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
 }
 
 static int sceZlibDecompress(u32 OutBuffer, int OutBufferLength, u32 InBuffer, u32 Crc32Addr) {
-	return CommonDecompress(MAX_WBITS, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
+	return CommonDecompress(15, OutBuffer, OutBufferLength, InBuffer, Crc32Addr);
 }
 
 const HLEFunction sceDeflt[] = {