Fix the warnings better

decode.cpp

@@ -277,7 +277,7 @@ void decode(char *fname, int z, unsigned x, unsigned y, std::set<std::string> co
 	struct stat st;
 	std::vector<zxy> tiles;
 
-	char *pmtiles_map;
+	char *pmtiles_map = NULL;
 	std::vector<pmtiles::entry_zxy> entries;
 	bool is_pmtiles = false;
 

pmtiles/pmtiles.hpp

@@ -166,11 +166,11 @@ struct entryv3 {
 	}
 };
 
-static struct {
+struct entryv3_cmp {
 	bool operator()(entryv3 a, entryv3 b) const {
 		return a.tile_id < b.tile_id;
 	}
-} entryv3_cmp;
+};
 
 struct entry_zxy {
 	uint8_t z;

pmtiles_file.cpp

@@ -263,7 +263,7 @@ void mbtiles_map_image_to_pmtiles(char *fname, metadata m, bool tile_compression
 
 	// finalize PMTiles archive.
 	{
-		std::sort(entries.begin(), entries.end(), pmtiles::entryv3_cmp);
+		std::sort(entries.begin(), entries.end(), pmtiles::entryv3_cmp());
 
 		std::string root_bytes;
 		std::string leaves_bytes;