Fix asmdiff.sh to work without DKP, also improve the makefile command for recognizing a toolchain.

The new command requires the toolchain binary path to exist in the file system before building using a toolchain (to handle the case where gba-dev is uninstalled but $(DEVKITARM) still exists))

asmdiff.sh

@@ -1,6 +1,11 @@
 #!/bin/bash
 
-OBJDUMP="$DEVKITARM/bin/arm-none-eabi-objdump -D -bbinary -marmv4t -Mforce-thumb"
+if [[ -d "$DEVKITARM/bin/" ]]; then
+    OBJDUMP_BIN="$DEVKITARM/bin/arm-none-eabi-objdump"
+else
+    OBJDUMP_BIN="arm-none-eabi-objdump"
+fi
+OBJDUMP="$OBJDUMP_BIN -D -bbinary -marmv4t -Mforce-thumb"
 OPTIONS="--start-address=$(($1)) --stop-address=$(($1 + $2))"
 $OBJDUMP $OPTIONS baserom.gba > baserom.dump
 $OBJDUMP $OPTIONS pokeemerald.gba > pokeemerald.dump