Handle more numeric literal syntax errors in linker scripts

test/link/script-lone-dollar.out

@@ -1,3 +1,3 @@
-error: No hexadecimal digits found after '$'
+error: Invalid integer constant, no digits after '$'
     at script-lone-dollar.link(1)
 Linking failed with 1 error

test/link/script-lone-percent.out

@@ -1,3 +1,3 @@
-error: No binary digits found after '%'
+error: Invalid integer constant, no digits after '%'
     at script-lone-percent.link(1)
 Linking failed with 1 error

test/link/script-num-fmt.link

@@ -1,9 +1,11 @@
 ROM0
 	org 4_2
 	org %10_10_10
-	org &52_
-	org $2A_
-	org 0b101_010
-	org 0o5_2
+	org &52_ ; trailing '_'
+	org $2A_ ; trailing '_'
+	org 0b101__010 ; '_' after another '_'
+	org 0o__5_2 ; '_' after another '_'
 	org 0x2_A
-	org 41 ; Error!
+	org 41 ; different value
+	org %_ ; no digits
+	org 0x__ ; no digits

test/link/script-num-fmt.out

@@ -1,3 +1,25 @@
+error: Invalid integer constant, trailing '_'
+    at script-num-fmt.link(4)
+error: Invalid integer constant, trailing '_'
+    at script-num-fmt.link(5)
+error: Invalid integer constant, '_' after another '_'
+    at script-num-fmt.link(6)
+error: Invalid integer constant, '_' after another '_'
+    at script-num-fmt.link(7)
 error: Cannot decrease the current address (from $002a to $0029)
     at script-num-fmt.link(9)
-Linking failed with 1 error
+error: Invalid integer constant, no digits after '%'
+    at script-num-fmt.link(10)
+error: Invalid integer constant, trailing '_'
+    at script-num-fmt.link(10)
+error: Cannot decrease the current address (from $002a to $0000)
+    at script-num-fmt.link(10)
+error: Invalid integer constant, '_' after another '_'
+    at script-num-fmt.link(11)
+error: Invalid integer constant, no digits after "0x"
+    at script-num-fmt.link(11)
+error: Invalid integer constant, trailing '_'
+    at script-num-fmt.link(11)
+error: Cannot decrease the current address (from $002a to $0000)
+    at script-num-fmt.link(11)
+Linking failed with 12 errors