Refactor how map file sections are printed

This makes size-0 sections print as "($0000 bytes)" instead of
"(0 bytes)", which is more consistent.

src/link/output.cpp

@@ -452,17 +452,10 @@ static void writeMapBank(SortedSections const &sectList, SectionType type, uint3
 
 		prevEndAddr = sect->org + sect->size;
 
+		fprintf(mapFile, "\tSECTION: $%04" PRIx16, sect->org);
 		if (sect->size != 0)
-			fprintf(
-			    mapFile,
-			    "\tSECTION: $%04" PRIx16 "-$%04x ($%04" PRIx16 " byte%s) [\"",
-			    sect->org,
-			    prevEndAddr - 1,
-			    sect->size,
-			    sect->size == 1 ? "" : "s"
-			);
-		else
-			fprintf(mapFile, "\tSECTION: $%04" PRIx16 " (0 bytes) [\"", sect->org);
+			fprintf(mapFile, "-$%04x", prevEndAddr - 1);
+		fprintf(mapFile, " ($%04" PRIx16 " byte%s) [\"", sect->size, sect->size == 1 ? "" : "s");
 		printSectionName(sect->name, mapFile);
 		fputs("\"]\n", mapFile);
 

test/link/map-file/a.asm

@@ -25,3 +25,7 @@ wLabel1:: ds 6
 SECTION "hram", HRAM
 hLabel:: ds 7
 .local::
+
+SECTION "empty", ROM0[1]
+EmptyLabel::
+.local::

test/link/map-file/ref.out.map

@@ -10,6 +10,9 @@ ROM0 bank #0:
 	SECTION: $0000-$0000 ($0001 byte) ["rom0"]
 	         $0000 = Label0
 	         $0001 = Label0.local
+	SECTION: $0001 ($0000 bytes) ["empty"]
+	         $0001 = EmptyLabel.local
+	         $0001 = EmptyLabel
 	EMPTY: $0001-$3fff ($3fff bytes)
 	TOTAL EMPTY: $3fff bytes