Fix MODE=aarch64 cross-compiling

This change fixes a regression that happened some time ago when building
for AARCH64 using the vendored toolchain rather than cosmocc. The errors
that would show up `Relocations in generic ELF (EM: 62)` have been fixed

Author: jart

build/definitions.mk

@@ -92,6 +92,8 @@ ARCH = x86_64
 HOSTS ?= freebsd rhel7 xnu win10 openbsd netbsd
 endif
 
+ZIPOBJ_FLAGS += -a$(ARCH)
+
 ifeq ($(PREFIX),)
 ifeq ($(USE_SYSTEM_TOOLCHAIN),)
 ifeq ($(ARCH),x86_64)

third_party/python/BUILD.mk

@@ -4193,7 +4193,7 @@ $(THIRD_PARTY_PYTHON_HELLO_OBJS): private PYFLAGS += -C2 -m
 # this directory entry is at the tip of the tree
 # therefore building it requires special care
 o/$(MODE)/third_party/python/Lib/.zip.o: third_party/python/.python
-	@$(COMPILE) -wAZIPOBJ $(ZIPOBJ) -C2 $(OUTPUT_OPTION) third_party/python/.python
+	@$(COMPILE) -wAZIPOBJ $(ZIPOBJ) -a$(ARCH) -C2 $(OUTPUT_OPTION) third_party/python/.python
 
 # these need to be explictly defined because landlock make won't sandbox
 # prerequisites with a trailing slash.