Make considerably more progress on AARCH64

- Utilities like pledge.com now build
- kprintf() will no longer balk at 48-bit addresses
- There's a new aarch64-dbg build mode that should work
- gc() and defer() are mostly pacified; avoid using them on aarch64
- THIRD_PART_STB now has Arm Neon intrinsics for fast image handling

third_party/chibicc/chibicc.mk

@@ -10,6 +10,8 @@
 #   This makefile compiles and runs each test twice. The first with
 #   GCC-built chibicc, and a second time with chibicc-built chibicc
 
+ifeq ($(ARCH), x86_64)
+
 CHIBICC = o/$(MODE)/third_party/chibicc/chibicc.com
 CHIBICC_FLAGS =								\
 	-fno-common							\
@@ -111,6 +113,8 @@ THIRD_PARTY_CHIBICC_CHECKS = $(foreach x,$(THIRD_PARTY_CHIBICC_ARTIFACTS),$($(x)
 THIRD_PARTY_CHIBICC_OBJS = $(foreach x,$(THIRD_PARTY_CHIBICC_ARTIFACTS),$($(x)_OBJS))
 $(THIRD_PARTY_CHIBICC_OBJS): $(BUILD_FILES) third_party/chibicc/chibicc.mk
 
+endif
+
 .PHONY: o/$(MODE)/third_party/chibicc
 o/$(MODE)/third_party/chibicc:						\
 		o/$(MODE)/third_party/chibicc/test			\

third_party/chibicc/test/test.mk

@@ -10,6 +10,8 @@
 #   This makefile compiles and runs each test twice. The first with
 #   GCC-built chibicc, and a second time with chibicc-built chibicc
 
+ifeq ($(ARCH), x86_64)
+
 PKGS += THIRD_PARTY_CHIBICC_TEST
 
 THIRD_PARTY_CHIBICC_TEST_A = o/$(MODE)/third_party/chibicc/test/test.a
@@ -75,6 +77,8 @@ o/$(MODE)/third_party/chibicc/test/%.o:						\
 
 o/$(MODE)/third_party/chibicc/test/int128_test.o: private QUOTA = -M1024m
 
+endif
+
 .PHONY: o/$(MODE)/third_party/chibicc/test
 o/$(MODE)/third_party/chibicc/test:						\
 		$(THIRD_PARTY_CHIBICC_TEST_BINS)				\