Switch to toybox stat on macOS too.

Bug: http://b/139450866
Test: builds
Change-Id: I1a992a63fbf5181a48262901730b8b67661cc259

core/combo/HOST_darwin-x86_64.mk

@@ -59,8 +59,3 @@ $(hide) $(PRIVATE_CXX) \
         $(PRIVATE_LDFLAGS) \
         $(PRIVATE_LDLIBS)
 endef
-
-# $(1): The file to check
-define get-file-size
-stat -f "%z" $(1)
-endef

core/combo/HOST_linux-x86.mk

@@ -23,8 +23,3 @@ endef
 
 ############################################################
 ## Macros after this line are shared by the 64-bit config.
-
-# $(1): The file to check
-define get-file-size
-stat -c "%s" "$(1)" | tr -d '\n'
-endef

core/definitions.mk

@@ -2678,9 +2678,9 @@ endef
 ###########################################################
 
 # $(1): The file to check
-ifndef get-file-size
-$(error HOST_OS must define get-file-size)
-endif
+define get-file-size
+stat -c "%s" "$(1)" | tr -d '\n'
+endef
 
 # $(1): The file(s) to check (often $@)
 # $(2): The partition size.