Fix RANGE ERROR STOPPED AT 8214

On a 48k Apple II, the BLTU2 call throws an error,
even when there is nothing to copy in the LC segment.

Add an alternative LC copy, based on memcpy, to an
extra file that the user can link in as with iobuf-0800.

This memcpy-based version allows our programs to run on
Integer ROM apple2. It costs 21 bytes in binary size,
plus memcpy (60 bytes in binary size + RAM use) if it
wasn't already linked in.

libsrc/apple2/extra/lc-copy-memcpy.s

@@ -0,0 +1,33 @@
+;
+; Colin Leroy-Mira, 06.03.2025
+;
+; Copy the LC segment from the end of the binary to the Language Card
+; using _memcpy. This allows running apple2 programs on the original
+; Integer ROM Apple ][.
+;
+
+        .export         bltu2
+
+        .import         _memcpy, pushax
+        .import         __ONCE_LOAD__, __ONCE_SIZE__    ; Linker generated
+        .import         __LC_START__, __LC_LAST__       ; Linker generated
+
+        .segment        "ONCE"
+
+bltu2:
+        ; Get the destination start address.
+        lda     #<__LC_START__
+        ldx     #>__LC_START__
+        jsr     pushax
+
+        ; Get the source start address.
+        lda     #<(__ONCE_LOAD__ + __ONCE_SIZE__)
+        ldx     #>(__ONCE_LOAD__ + __ONCE_SIZE__)
+        jsr     pushax
+
+        ; Set the length
+        lda     #<(__LC_LAST__ - __LC_START__)
+        ldx     #>(__LC_LAST__ - __LC_START__)
+
+        ; And do the copy
+        jmp     _memcpy