Revert "makefile: remove unnecessary ARM-specific targets"

This reverts commit ecd0f2dde7.

These targets that are not native builds. They are for builds
portable within processors of a given family.

'make release' used to not work to build a native build on ARM, but that
has been fixed. These targets are unrelated to the native build.

Makefile

@@ -58,6 +58,14 @@ release-all:
 	mkdir -p build/release
 	cd build/release && cmake -D BUILD_TESTS=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
 
+release-arm6:
+	mkdir -p build/release
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv6zk" -D BUILD_64=OFF -D NO_AES=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+
+release-arm7:
+	mkdir -p build/release
+	cd build/release && cmake -D BUILD_TESTS=OFF -D ARCH="armv7-a" -D BUILD_64=OFF -D NO_AES=ON -D CMAKE_BUILD_TYPE=release ../.. && $(MAKE)
+	
 release-static: release-static-64
 
 release-static-64: