RGBLINK lists local symbols when encountering an unknown symbol reference (#1496)

test/link/symbols/unknown/a.asm

@@ -0,0 +1,2 @@
+section "a", rom0
+ld hl, Label

test/link/symbols/unknown/b.asm

@@ -0,0 +1,2 @@
+section "b", rom0
+Label:

test/link/symbols/unknown/c.asm

@@ -0,0 +1 @@
+def Label equ 42

test/link/symbols/unknown/d.asm

@@ -0,0 +1 @@
+def Label = 123

test/link/symbols/unknown/e.asm

@@ -0,0 +1,2 @@
+section "e", wram0
+Label:

test/link/symbols/unknown/out.err

@@ -0,0 +1,6 @@
+error: symbols/unknown/a.asm(2): Unknown symbol "Label"
+    A label with that name is defined but not exported at symbols/unknown/b.asm(2)
+    A constant with that name is defined but not exported at symbols/unknown/c.asm(1)
+    A constant with that name is defined but not exported at symbols/unknown/d.asm(1)
+    ...and 1 more symbol with that name is defined but not exported
+Linking failed with 1 error

test/link/test.sh

@@ -8,10 +8,11 @@ gbtemp="$(mktemp)"
 gbtemp2="$(mktemp)"
 outtemp="$(mktemp)"
 outtemp2="$(mktemp)"
+outtemp3="$(mktemp)"
 
 # Immediate expansion is the desired behavior.
 # shellcheck disable=SC2064
-trap "rm -f ${otemp@Q} ${gbtemp@Q} ${gbtemp2@Q} ${outtemp@Q} ${outtemp2@Q}" EXIT
+trap "rm -f ${otemp@Q} ${gbtemp@Q} ${gbtemp2@Q} ${outtemp@Q} ${outtemp2@Q} ${outtemp3@Q}" EXIT
 
 tests=0
 failed=0
@@ -316,7 +317,7 @@ for i in section-union/*.asm; do
 	evaluateTest
 done
 
-test="symbols"
+test="symbols/good"
 startTest
 "$RGBASM" -o "$otemp" "$test"/a.asm
 "$RGBASM" -o "$gbtemp2" "$test"/b.asm
@@ -327,6 +328,18 @@ tryDiff "$test"/ref.out.sym "$outtemp2"
 tryCmpRom "$test"/ref.out.bin
 evaluateTest
 
+test="symbols/unknown"
+startTest
+"$RGBASM" -o "$otemp" "$test"/a.asm
+"$RGBASM" -o "$gbtemp" "$test"/b.asm
+"$RGBASM" -o "$gbtemp2" "$test"/c.asm
+"$RGBASM" -o "$outtemp" "$test"/d.asm
+"$RGBASM" -o "$outtemp2" "$test"/e.asm
+continueTest
+rgblinkQuiet "$otemp" "$gbtemp" "$gbtemp2" "$outtemp" "$outtemp2" 2>"$outtemp3"
+tryDiff "$test"/out.err "$outtemp3"
+evaluateTest
+
 if [[ "$failed" -eq 0 ]]; then
 	echo "${bold}${green}All ${tests} tests passed!${rescolors}${resbold}"
 else