Normalize `arm64` to `aarch64`.

This ensures that we call ARM64 `aarch64` on all platform, which aren't
MacOS or Windows. And it fixes the bug, that `arm64` was normalized to
`arm`, making incompatible savegames between 32 bit and 64 bit ARM
loadable. Leading to crashes.

Makefile

@@ -111,7 +111,7 @@ endif # windows but MINGW_CHOST not defined
 else
 ifneq ($(YQ2_OSTYPE), Darwin)
 # Normalize some abiguous YQ2_ARCH strings
-YQ2_ARCH ?= $(shell uname -m | sed -e 's/i.86/i386/' -e 's/amd64/x86_64/' -e 's/^arm.*/arm/')
+YQ2_ARCH ?= $(shell uname -m | sed -e 's/i.86/i386/' -e 's/amd64/x86_64/' -e 's/arm64/aarch64/' -e 's/^arm.*/arm/')
 else
 YQ2_ARCH ?= $(shell uname -m)
 endif