Split librfu by function type (thumb/arm)

ld_script.txt

@@ -316,6 +316,8 @@ SECTIONS {
         src/agb_flash_1m.o(.text);
         src/agb_flash_mx.o(.text);
         src/agb_flash_le.o(.text);
+        asm/librfu_stwi.o(.text);
+        asm/librfu_intr.o(.text);
         asm/librfu.o(.text);
         src/isagbprn.o(.text);
         asm/libagbsyscall.o(.text);