Fix linking tiny overlay files (#755)

* Fix compatibility of rgblink -O and -t

The -t "tiny mode" option makes ROM0 cover 0x8000 bytes,
not 0x4000. The -O "overlay" option fills areas uncovered
by sections with data from an overlay file. These needed
to cooperate so that the calculated uncovered overlay size
does not exceed the actual size of the ROM.

Fixes #754

* Print link test names like asm tests do

* Make the three test.sh scripts more similar

test/link/overlay/a.asm

@@ -0,0 +1,2 @@
+SECTION "0", ROM0[0]
+DS $8000

test/link/test.sh

@@ -1,37 +1,44 @@
 #!/bin/bash
+
 export LC_ALL=C
 set -o pipefail
 
-otemp=$(mktemp)
-gbtemp=$(mktemp)
-gbtemp2=$(mktemp)
-outtemp=$(mktemp)
+otemp="$(mktemp)"
+gbtemp="$(mktemp)"
+gbtemp2="$(mktemp)"
+outtemp="$(mktemp)"
 rc=0
 
 trap "rm -f '$otemp' '$gbtemp' '$gbtemp2' '$outtemp'" EXIT
 
-bold=$(tput bold)
-resbold=$(tput sgr0)
-red=$(tput setaf 1)
-rescolors=$(tput op)
+bold="$(tput bold)"
+resbold="$(tput sgr0)"
+red="$(tput setaf 1)"
+green="$(tput setaf 2)"
+rescolors="$(tput op)"
+
+RGBASM=../../rgbasm
+RGBLINK=../../rgblink
+
+startTest () {
+	echo "$bold$green${i%.asm}...$rescolors$resbold"
+}
 
 tryDiff () {
-	if ! diff -u --strip-trailing-cr $1 $2; then
+	if ! diff -u --strip-trailing-cr "$1" "$2"; then
 		echo "${bold}${red}${i%.asm}.out mismatch!${rescolors}${resbold}"
 		false
 	fi
 }
 
 tryCmp () {
-	if ! cmp $1 $2; then
-		../../contrib/gbdiff.bash $1 $2
+	if ! cmp "$1" "$2"; then
+		../../contrib/gbdiff.bash "$1" "$2"
 		echo "${bold}${red}${i%.asm}.out.bin mismatch!${rescolors}${resbold}"
 		false
 	fi
 }
 
-RGBASM=../../rgbasm
-RGBLINK=../../rgblink
 rgblink() {
 	out="$(env $RGBLINK "$@")" || return $?
 	if [[ -n "$out" ]]; then
@@ -41,6 +48,7 @@ rgblink() {
 }
 
 for i in *.asm; do
+	startTest
 	$RGBASM -o $otemp $i
 
 	# Some tests have variants depending on flags
@@ -91,13 +99,16 @@ done
 
 # These tests do their own thing
 
+i="bank-const.asm"
+startTest
 $RGBASM -o $otemp bank-const/a.asm
 $RGBASM -o $gbtemp2 bank-const/b.asm
 rgblink -o $gbtemp $gbtemp2 $otemp > $outtemp 2>&1
-i="bank-const.asm" tryDiff bank-const/err.out $outtemp
+tryDiff bank-const/out.err $outtemp
 rc=$(($? || $rc))
 
 for i in fragment-align/*; do
+	startTest
 	$RGBASM -o $otemp $i/a.asm
 	$RGBASM -o $gbtemp2 $i/b.asm
 	rgblink -o $gbtemp $otemp $gbtemp2 2>$outtemp
@@ -110,27 +121,46 @@ for i in fragment-align/*; do
 	fi
 done
 
+i="high-low.asm"
+startTest
 $RGBASM -o $otemp high-low/a.asm
 rgblink -o $gbtemp $otemp
 $RGBASM -o $otemp high-low/b.asm
 rgblink -o $gbtemp2 $otemp
-i="high-low.asm" tryCmp $gbtemp $gbtemp2
+tryCmp $gbtemp $gbtemp2
 rc=$(($? || $rc))
 
+i="overlay.asm"
+startTest
+$RGBASM -o $otemp overlay/a.asm
+rgblink -o $gbtemp -t -O overlay/overlay.gb $otemp > $outtemp 2>&1
+# This test does not trim its output with 'dd' because it needs to verify the correct output size
+tryDiff overlay/out.err $outtemp
+rc=$(($? || $rc))
+tryCmp overlay/out.gb $gbtemp
+rc=$(($? || $rc))
+
+i="section-union/good.asm"
+startTest
 $RGBASM -o $otemp section-union/good/a.asm
 $RGBASM -o $gbtemp2 section-union/good/b.asm
 rgblink -o $gbtemp -l section-union/good/script.link $otemp $gbtemp2
 dd if=$gbtemp count=1 bs=$(printf %s $(wc -c < section-union/good/ref.out.bin)) > $otemp 2>/dev/null
-i="section-union/good.asm" tryCmp section-union/good/ref.out.bin $otemp
+tryCmp section-union/good/ref.out.bin $otemp
 rc=$(($? || $rc))
+
+i="section-union/fragments.asm"
+startTest
 $RGBASM -o $otemp section-union/fragments/a.asm
 $RGBASM -o $gbtemp2 section-union/fragments/b.asm
 rgblink -o $gbtemp $otemp $gbtemp2
 dd if=$gbtemp count=1 bs=$(printf %s $(wc -c < section-union/fragments/ref.out.bin)) > $otemp 2>/dev/null
-i="section-union/fragments.asm" tryCmp section-union/fragments/ref.out.bin $otemp
+tryCmp section-union/fragments/ref.out.bin $otemp
 rc=$(($? || $rc))
+
 for i in section-union/*.asm; do
-	$RGBASM -o $otemp   $i
+	startTest
+	$RGBASM -o $otemp $i
 	$RGBASM -o $gbtemp2 $i -DSECOND
 	if rgblink $otemp $gbtemp2 2>$outtemp; then
 		echo -e "${bold}${red}$i didn't fail to link!${rescolors}${resbold}"