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/Debugger/SymbolMap.cpp

@@ -34,7 +34,7 @@
 #include <string_view>
 #include <unordered_map>
 
-#include "zlib.h"
+#include "Common/Data/Encoding/Compression.h"
 
 #include "ext/armips/Core/Assembler.h"
 
@@ -82,31 +82,32 @@ void SymbolMap::Clear() {
 bool SymbolMap::LoadSymbolMap(const Path &filename) {
 	Clear();
 
-	// TODO(scoped): Use gzdopen instead.
-
-#if defined(_WIN32) && defined(UNICODE)
-	gzFile f = gzopen_w(filename.ToWString().c_str(), "r");
-#else
-	gzFile f = gzopen(filename.c_str(), "r");
-#endif
-
-	if (f == Z_NULL)
+	// The map may be gzipped (bCompressSymbols) or plain text.
+	std::string contents;
+	if (!File::ReadBinaryFileToString(filename, &contents))
 		return false;
-
-	//char temp[256];
-	//fgets(temp,255,f); //.text section layout
-	//fgets(temp,255,f); //  Starting        Virtual
-	//fgets(temp,255,f); //  address  Size   address
-	//fgets(temp,255,f); //  -----------------------
+	if (contents.size() >= 2 && (u8)contents[0] == 0x1f && (u8)contents[1] == 0x8b) {
+		std::string plain;
+		if (!decompress_string(contents, &plain))
+			return false;
+		contents.swap(plain);
+	}
+	size_t pos = 0;
 
 	bool started = false;
 	bool hasModules = false;
 
-	while (!gzeof(f)) {
+	while (pos < contents.size()) {
 		char line[512], temp[256] = {0};
-		char *p = gzgets(f, line, 512);
-		if (p == NULL)
-			break;
+		size_t end = contents.find('\n', pos);
+		if (end == std::string::npos)
+			end = contents.size();
+		const size_t len = std::min(end - pos, sizeof(line) - 1);
+		memcpy(line, contents.data() + pos, len);
+		line[len] = '\0';
+		pos = end + 1;
+		if (len == 0)
+			continue;
 
 		// Chop any newlines off.
 		for (size_t i = strlen(line) - 1; i > 0; i--) {
@@ -205,7 +206,6 @@ bool SymbolMap::LoadSymbolMap(const Path &filename) {
 			}
 		}
 	}
-	gzclose(f);
 	activeNeedUpdate_ = true;
 	SortSymbols();
 	return started;
@@ -233,81 +233,13 @@ bool SymbolMap::SaveSymbolMap(const Path &filename) const {
 
 	std::string data;
 	buf.TakeAll(&data);
-	FILE *file = File::OpenCFile(filename, "wb");
-	if (file == nullptr) {
-		return false;
-	}
 	if (g_Config.bCompressSymbols) {
-		uInt out_size = 4096;
-		Bytef *out_data = (Bytef *)std::malloc(out_size);
-		if (out_data == nullptr) {
-			fclose(file);
+		std::string compressed;
+		if (!compress_string(data, &compressed, 9, 31))
 			return false;
-		}
-		z_stream strm;
-		strm.zalloc = nullptr;
-		strm.zfree = nullptr;
-		strm.opaque = nullptr;
-		if (deflateInit2(&strm, Z_BEST_COMPRESSION, Z_DEFLATED, MAX_WBITS + 16, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
-			std::free(out_data);
-			fclose(file);
-			return false;
-		}
-		strm.next_in = (Bytef *)data.data();
-		strm.avail_in = (u32)data.size();
-		strm.next_out = out_data;
-		strm.avail_out = out_size;
-		int flush = Z_NO_FLUSH;
-		for (;;) {
-			int status = deflate(&strm, flush);
-			switch (status) {
-				case Z_OK:
-				case Z_STREAM_END:
-					if (strm.avail_out != out_size) {
-						fwrite(out_data, 1, out_size - strm.avail_out, file);
-					}
-					break;
-				case Z_BUF_ERROR:
-					{
-						std::free(out_data);
-						uInt new_out_size = 2 * out_size;
-						if (new_out_size < out_size) {
-							deflateEnd(&strm);
-							fclose(file);
-							return false;
-						}
-						out_size = new_out_size;
-						out_data = (Bytef *)std::malloc(out_size);
-						if (out_data == nullptr) {
-							deflateEnd(&strm);
-							fclose(file);
-							return false;
-						}
-					}
-					break;
-				default:
-					deflateEnd(&strm);
-					std::free(out_data);
-					fclose(file);
-					return false;
-			}
-			if (status == Z_STREAM_END) {
-				break;
-			}
-			if (strm.avail_in == 0) {
-				flush = Z_FINISH;
-			}
-			strm.next_out = out_data;
-			strm.avail_out = out_size;
-		}
-		deflateEnd(&strm);
-		std::free(out_data);
-	} else {
-		// Just plain write it.
-		fwrite(data.data(), 1, data.size(), file);
+		data.swap(compressed);
 	}
-	fclose(file);
-	return true;
+	return File::WriteDataToFile(false, data.data(), data.size(), filename);
 }
 
 bool SymbolMap::LoadNocashSym(const Path &filename) {