More performance improvements
Instead of using `x := $(x) foo`, make sure `x` is initialized first,
then use `x += foo`.
For a aosp-master/aosp_crosshatch-userdebug build, this takes the build
from 49s to 33s (no significant difference in peak memory)
Bug: 158488548
Test: build-aosp_crosshatch.ninja is the same before/after
Change-Id: I41fb7611030dd3ba824f896a9c9eadbdd218f464
diff --git a/core/cc_prebuilt_internal.mk b/core/cc_prebuilt_internal.mk
index 1d959b5..99b7d0f 100644
--- a/core/cc_prebuilt_internal.mk
+++ b/core/cc_prebuilt_internal.mk
@@ -75,7 +75,7 @@
built_module := $(LOCAL_BUILT_MODULE)
ifdef prebuilt_module_is_a_library
-EXPORTS_LIST := $(EXPORTS_LIST) $(intermediates)
+EXPORTS_LIST += $(intermediates)
EXPORTS.$(intermediates).FLAGS := $(foreach d,$(LOCAL_EXPORT_C_INCLUDE_DIRS),-I $(d))
EXPORTS.$(intermediates).DEPS := $(LOCAL_EXPORT_C_INCLUDE_DEPS)