litecross: automatically determine LINUX_ARCH for kernel headers

litecross/Makefile

@@ -157,6 +157,10 @@ install-toolchain: | obj_toolchain/.lc_built
 	ln -sf $(TARGET)-gcc $(DESTDIR)$(OUTPUT)/bin/$(TARGET)-cc
 
 ifneq ($(LINUX_SRCDIR),)
+TARGET_ARCH = $(firstword $(subst -, ,$(TARGET)))
+TARGET_ARCH_MANGLED = $(patsubst i%86,x86,$(patsubst aarch64%,arm64%,$(TARGET_ARCH)))
+LINUX_ARCH_LIST = $(sort $(notdir $(wildcard $(LINUX_SRCDIR)/arch/*)))
+LINUX_ARCH = $(firstword $(foreach a,$(LINUX_ARCH_LIST),$(findstring $(a),$(TARGET_ARCH_MANGLED))))
 ifneq ($(LINUX_ARCH),)
 all: kernel-headers
 install: install-kernel-headers